So when exactly was the Law/Chaos war?

I'm not aware of an ice age in Krynn, Athas, Aebrynis, or Eberron, but honestly I'm tired and don't want to bother to look it up. Krynn is a very young world.

Well, for Eberron it is assumed since that world is very much like the prime and is all-inclusive. Since that means that Eberron WILL contain Ice Age megafauna in some areas, then yes, that indicates that Eberron had an ice age.
Athas did not, however.
Krynn and Aebrynis I cannot speak of as I know too little about them, but Mystara certainly did (even though Mystara is only partially related to the rest of the D&D world)

Anyway, despite any nitpicking, I actually quite like your theory, and I'd be very happy if the Law-Chaos war did result in an ice age across the Prime.

Not just an ice age, but also Triassic (dinosaur age), which means hot and dry, and Permian (means the same, but to a greater degree), and possibly even a Permian Triassic extinction event on many (but not every) primeworld-- the result of Fire's dominance reaching disastrous proportions. (the Permian Triassic extinction event was caused by a natural warming and drying period caused by a small-scale extinction event resulting in Global Warming *due partially to the formation of Pangaea, which put the planet's life under a LOT of stress. See, life is most abundant in shallow seas and on land near the coasts. Pangaea greatly reduced the surface area of such habitats, and would have resulted in really, superharsh continental climates far inland. Continental climates are caused by inland weather fronts and are categorized by hot summers and cold winters, as opposed to Marine climates which are categorized by warm winters and cool summers. Continental climates are also far drier than marine climates.*, and then the formation of the Siberian Traps. You know that volcano belt and lava lake around the Reptite Castle in Chrono Trigger? Well, it was like that, except it spanned all of Siberia. Yes, a lake of lava and superactive volcanoes the size of an entire continent. This caused catastropic global warming, which melted huge amounts of frozen submarine methane deposits, and thus disaster strikes.
The global warming led to acidification of the ocean, and the melting of methane created a habitat friendly to green sulfur bacteria, which process methane into hydrogen sulfide-- a nasty gas which is highly toxic to plant life, causes water in which it is bound to to become anoxic, creates acid rain, and depletes the ozone layer. With the destruction of most plant life, there was little left to filter out waterborne and atmospheric pollutants or reduce the amazingly high CO2 levels. Oh, yeah, methane is also 50x more potent as a greenhouse gas than CO2.)

The result? Well, I think the opening on the Wikipedia article speaks for itself.

an extinction event that occurred 251.4 million years ago, forming the boundary between the Permian and Triassic geologic periods. It was the Earth's most severe extinction event, with up to 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct; it is the only known mass extinction of insects. 57% of all families and 83% of all genera were killed. Because so much biodiversity was lost, the recovery of life on Earth took significantly longer than after other extinction events. This event has been described as the "mother of all mass extinctions".

The species worst affected were calcium carbonate shelled organisms (molluscs, cephalopods, corals), because acidic PH levels interfere with their ability to absorb calcium carbonate from the environment, marine organisms, and terrestrial plants (for which hydrogen sulfide is extremely toxic).

The Cretatious-Tertiary extinction event (or K-T, the one which layfolks and scientists are most familiar with-- the one which wiped out the dinosaurs) may not be so easily explained, however. Would fire and earth dominance greatly increase the number of circulating asteroids, comets, and meteorites in many crystal spheres? That doesn't seem very likely, to me. I would have to say that something else disastrous led to the bolide impacts on many prime worlds that ended the reign of the dinosaurs (though certainly Elemental Fire was still dominant during this time).

Ordovician-Silurian Extinction: The 3rd largest known extinction event. Appears to have been caused by an ice age.

Triassic-Jurassic Extinction: A smaller extinction than the K-T (the 4th largest known extinction event in earth's history), but still huge nonetheless. Evidence suggests this was caused by a repeat of history-- the Permian Triassic happening all over again (you'd think Imix would have learned his lesson the first time around...)

Late Devonian: Doesn't look like there's a very good consensus over what caused this one. Evidence suggests a combination of global cooling and anoxic marine conditions-- an odd combination. This one is unlikely to be the result of anything going on in the Inner Planes since the extinction event seems to be tied to the rise of vascular plants. For the D&D world, this would either be linked to Prime parralelism or to the blunders of a primordial plant god. This would have caused an absolutely massive ecological change, filling an all new niche, since vasculature allows terrestrial plants to reach great heights. The vascular plants are also able to send their roots deep into the soil (unlike nonvascular plants), which gave them a monumental competitive advantage over non-vascular terrestrial plants.

BTW, I am not surprised that Demogorgon was the first Tanar'ri. The Outsiders and Elementals seem to follow the age old rule of "the older the organism, the more powerful". We see this with Asmodeus and Ogremoch, as well (Ogremoch and Sunnis are the eldest of the archomentals, and therefore the most powerful. OTOH, Zaaman Rul is the youngest and weakest of the archomentals.)

Also, there is a 2E book (either one of the Monstrous Arcana books about the Sahuagin or Sea of Fallen Stars, IIRC) which claims that Demogorgon had a mother, and even gives her name. However, this could simply be an embellishment of the race's mythology.

When would the Baernaloths have come into being, though? Before or after sentient life (other than draedens) on the Prime?
The claim "from the mists of creation" (in the Timeline topic), assuming that's verbatim, means extremely little, since "The Creation" part of the Creation Cycle is not a single, instantaneous event or anything close to that.

Probably the forces of Law, Chaos, Good, and Evil were knocking about the unformed outer planes for a very long time, and they were exactly the sorts of nuisances the draedens got so upset by. If you believe the Astral Plane is younger than the raw potential of the Ethereal or the balanced substance of the Material Plane, then these alignment forces are probably younger still. But they're older than just about everything else.

I already explained in the "Do the Planes have to be Infinite?" topic why logic SOLIDLY dictates that the Ethereal is indeed much older than the Astral. Belief hasn't always been there, but potential has always existed, and before the Astral existed in any form, Belief would have been under the puryance of the Ethereal, so that would have covered belief by the Draedens until the Astral became a full, separate plane. However, I believe that the Astral is far, far older than the Outer or Material planes. Whether it's older or younger than the Elemental planes, I have no idea.

Lolth was "named tanar'ri" around 30,000 years ago
That makes little sense to me. The Crown Wars were 10,000 years ago, and that's the general age IIRC of the split between the elder elf groups on Oerth as well-- the split came about because of Lolth's fall from grace, and the Drow's exile to the Underdark is supposed to coincide with Araushnee's exile from the Seldarine. There's no friggin' way that Araushnee could have fallen and become a Tanar'ri and keep it secret from Corellon and the Celestials for nearly 20,000 years. I could see this if it occured 5,000, or even 10,000 years earlier, but 20,000? Not only that, but to be listed as a Tanar'ri at that time means that her fall from grace was already complete AT THAT POINT.

The whole situation with fallen spider-goddesses, elven heroes, and orc hordes seems very much in concert with the way things work in the modern era, not the antediluvian epoch of alien madness. Probably the Seldarine weren't even around yet during the age of the obyriths and wind dukes.
That's what I assumed, yeah.

On the Forgotten Realms timeline, which is the most developed history of any D&D world, the time of the Tearfall that divided the Days of Thunder from the Dawn Age (approximately 32,370 years ago) seems a perfect time to divide the obyrith era from the modern era. There was death and mass extinctions (that's when dinosaurs lost their dominance, I think), probably a minor ice age, the dragons and giants arrived after that point, and that's when Toril was divided from Aebir. It's exactly the sort of game-changing event that I'd expect, even if there's no causal relationship between the Tearfall (which was an asteroid that crashed into the planet, creating the Sea of Fallen Stars) and the Battle of Pesh. I don't think they'd necessarily happen perfectly simultaneously, but around the same time.

Wait, wait, dragons appeared AFTER the fall of the dinosaurs?

They might conceivably have originally formed in the Inner Planes as the elder elementals began to form into factions, and later on migrated to the Astral Plane when that came into being.
I was going to state my doubt in this, but looking at their stats, Yugoloths do indeed possess fire-subtype spell-like abilities. So you may well be onto something.

You mentioned that Pazuzu is an Obyrith turning into a Tanar'ri. I have no idea if that's mentioned in canon or if it's just your interpretation of the inconsistency, but if it's the latter, I like it. It makes me wonder if Juiblex is in the same boat. He possesses a form that you'd really expect out of an Obyrith, even though he's a Tanar'ri. One would expect that if so, then he was likely one of the first Obyriths.
One thing is obvious with the Obyrith: power does not = age. If this were so, then nearly all the remaining Obyriths would be far more powerful than even Demogorgon, or at least as powerful as the other big four (the difference in power springing SOLELY from lack of worshippers and a few having their powers stolen or siphoned off by other Obyrith/Tanar'ri)

Here's the chant on that theory: the inners planes, seat of elements and buildings blocks of nature, appeared first, the ethereal plane came second, falowed by the prime material plane, where elements combine and formed mortals, mortals create knowledge, and knowledge formed the astral, the bridge to belief, and with the developmen of belief came the outer planes. -HG 37

Yeah, I'm well aware of that quote, and the first part doesn't make sense, especially from what we know from Guide to the Ethereal. The elemental planes lack the capacity to create protomatter, plus protomatter (the buildingblocks of the Ethereal) = possibility and potential. Without possibility, there can be no inner planes or anything else. It also makes no sense that "mortals create knowledge", because the Baernaloths, Yugoloths, Aphancts, etc. came BEFORE the first mortals, and would have been spawned by belief (esp. the Baernaloths).

Well, here's what I have for a timeline thus far. Please tell me if there are any mistakes. (A few, such as the order in which the draeden go to sleep, the imprisonment of Tharizdun, and the rise of Elemental civilization, are mostly speculation)

--The Beginning-- Only the Ethereal and a vast void exist. The Draeden are still thriving from the latter half of the last creation cycle's apocalypse.

--The Elemental Planes are spawned in the Ethereal as Demiplanes. Elementals appear. At the same time, the first generation of Protogenoi are born (elemental and ooze-like primordial powers), including Ptah, Uranus, Ananake, Chronus, Phanes, Nyx, Erebus, Gaea, Tartarus, Kossuth, Istishia, Akadi, and Grumbar.

--The Elemental Planes become full-fledged planes; the Astral is created.

--The elements begin to leak into a demiplane which will eventually becomes the Prime Material Plane.

--The Positive and Negative Energy Planes become demiplanes; Phanes (a pure positive energy power) splits into several individual powers, including Eros *not the same one as Aphrodite's son*, Thesis, and Phusis.

--The second generation of Protogenoi are born: Oceanus (generally listed as a Titan, but given that most of his offspring were rivers, I think it's safe to assume he is at least half elemental), Pontus, the Ourea (plural), the Nesoi (plural), Nyx's and Erebus's offspring, and the first generation of the Titans. (see post #81 for a list of these offspring) (this entry is not finished, but I'm placing it here as a marker)

--After discovering that the Astral Void can be manipulated with the power of belief, a major schism forms between the Protogenoi when many decide to migrate to the Outer Planes. Many others stay behind, and a considerable percentage of these take exception to the idea of the migration, insisting that belief, like everything else, should be under the purview of the elemental planes and ethereal. Minor skirmishes and wars erupt between the two groups when some of the protogenoi attempt to prevent the migration. Ultimately, the two groups go their separate ways, and a massive migration takes place, with roughly 60 to 70% of the Protogenoi leaving for the Astral Void.

--The four cardinal races along with the Protogenoi begin to manipulate the Astral Void, and four unformed outer planes eventually spring into existence.

--The third generation of the Protogenoi are born, mostly Oceanus's progency.
This generation also includes several lunar and solar deities, such as Selune, Shar, Solinari, Nuitari, etc. (this entry is not finished, but I'm placing it here as a marker)

--The baernaloths and three other primordial outsider races stagger forth from the Astral, each representing one of the cardinal alignments.

--The four cardinal races and Protogenoi go to war with the Draedens over the right to form the Outer Planes. During this war, countless Draeden and Protogenoi are slain. Among the slain Protogenoi include Thesis (subsumed by Metis and Tethys) and Tartarus (whose corpse forms the core of what would later become Carceri)
This war results either in a draw, or a loss for the Draedens, who decide to go to sleep until the powers no longer exist. One by one, Draedens go into a death-like slumber over the course of millions of years.

--The baernaloths spawn the yugoloths, the chaotic progenitor race spawn the Proteans, and the other two primordial races also spawn an outsider race, for the purpose of converting the rest of the void connecting to the Astral into their cardinal alignment.

--The River Styx forms.

--The elementals become civilized, developing written language and advanced civilizations.

--The fourth generation of Protogenoi are born-- mostly children of Eris, all borne asexually. (this entry is not finished, but I'm placing it here as a marker)

--A rebel baernaloth named Apomps creates the gehreleths from dead yugoloths and is exhiled with the gehreleths into Carcerci.
The first ultroloth, the General of Gehenna, creates the Heart of Darkness to expunge the taint of law and chaos from the yugoloths which become the larvae of the lower planes.

--The "impure" larvae migrate to the Abyss and Baator to evolve into the Obyrith and Baatorians, respectively.

--The Blood Queen inadvertently creates the Aboleth race when she brushes against the border between the Far-Realm and Multiverse (at the Demiplane of Prime to be exact). This results in a tiny nick in the fabric of space-time. Over time, this 'nick' weakens until it tears open, creating a rift between the two Multiverses, connecting to the Demiplane of Prime on our side. The Powers of Balance on the Far-Realm side manage to repair/seal the tear, but not before numerous lifeforms from their side manage to spill over, including several powers or creatures that would become powers, such as The Great Mother, Ghaunadaur, The Patient One, Temulea, and possibly Tharizdun.

--The souls of aboleth begin to take form as petitioners on the primordial outer planes.

--The Great Mother is driven insane by her exposure to the Multiverse.

--Tharizdun goes insane due to a combination of the effects of the Multiverse on his psyche and long-term contact with/befriending the Draeden. He decides to destroy the multiverse.

--The primordial powers all form a temporary alliance to stop Tharizdun's plans.

--The genies, mephits, and several other flesh-based species emerge on the Inner Planes, including the Vaati.

--Realizing he could lose, Tharizdun creates a contingency plan to release him from whatever imprisonment the Protogenoi place him in. Over the next several centuries, he slowly corrupts the Elder Elemental Eye, the Omnimental Lord and overgod of the Elemental pantheon.
Using the Eye, he creates the five Princes of Elemental Evil as a part of this failsafe in the following chronological order: Ogremoch, Imix, Olhydra, Cryonax, Yan-C-Bin, and Vesvolch. Shortly after, he fully absorbs the Eye as an aspect of himself. The battle against Tharizdun spawns over millenia.

--At the same time, The Positive and Negative Energy Planes spawn their own Princes of Elemental Neutrality to guard against possible infection with another of Tharizdun's Princes of Elemental Evil, and to serve as extensions of the plane's will. From the Positive Energy Plane is born Crystalle to guard the positively-charged crystals and lifepearls of the plane, while Sun Sing is born from the raw essence of Negative Energy and void to safeguard the plane from invasions of matter and energy. Tharizdun wastes no time attempting to corrupt both Archomentals. He fails utterly with Crystalle, but succeeds with Sun Sing.

--The Elemental Planes (but not Paraelemental Ice) each spawn an Archomental of good in response to the birth of each evil Archomental. Each good counterpart is of the opposite sex of the evil archomental.

--Without the Elder Elemental Eye to keep the elemental planes and their lords in check, the four elements become unbalanced, with the dominance swinging back and forth between different elements and paraelements.

--The Qorrash evolve as a separate genie race from the Djinn.

--Ogremoch and Yan-C-Bin learn of one another, while Imix and Olhydra learn of one another's existence. They immediately declare war against each other.

--Imix and Brista Pel learn of one another's existence and declare war (even though Imix is more preoccupied with Olhydra)

--The primordial powers and primordial races manage to defeat Tharizdun, then imprison him in an unknown demiplane.

--Imix and Brista Pel encounter one another for the first time, shocked by the appealing visage one another possesses. Brista Pel eventually becomes impregnated with Zaaman Rul.

--The baernaloths dissappear, and the ultroloths become the leaders of the yugoloths. The four outsider races develop written language and advanced civilization.

--The Windduke Empire rises.

--The Baatorians begin to explore the planes, eventually discovering the Obyriths in the Abyss; as the Obyriths stumble into Baator and find the Baatorians. Disgusted by one another, a skirmish breaks out before the surviving scouts return to their home plane to report their findings.

--Several modern outsider races emerge from the raw essence of their Outer Plane, such as the Eladrins, Angels, and Justicators.

--The last of the Draeden goes into a deep slumber.

--Justicators dispatched by Lawful forces travel across the Great Wheel until they encounter the Obyriths. Both races feel revulsion for one another, and a skirmish breaks out before the Justicators return to Proto-Mechanus to report their findings.

--The Obyriths explore the Inner Planes and encounter the Vaati. Disgusted, they rend as many as they can.

--They also encounter an Archomental of Elemental Neutrality named Sun Sing on the Negative Energy Plane. He takes grave offense at their arrogance as they attempt in vain to subdue and dominate "his" plane. Deciding that the Obyrith must learn a painful lesson and "learn their proper place", he follows them to their portals leading back to the Abyss. There, he infects and twists many of their portals in a region that would (in the future) split off to become the layer known as the "Plane of Infinite Portals". Many Obyrith perish when they step into previously safe portals that, unknown to them, now lead to the core of the Negative Energy Plane.

--In Mechanus, the beings of primal Order (the Twin Serpents, the One and Prime, the Cultivator, the Plotter, the Defender, and the Clockmaker) debate on what to do with this new-found information. One of the Serpents suggests they dispatch warriors to destroy the obyriths before they infect more of the planes, before they come to Mechanus to destroy them all. The others agree, and give most of the responsibility to the Serpent, who accepts it gladly. The others return to their austere contemplations of mathematics.

--The Serpent of War, also called Aeshma, leaves its twin, the Serpent of Wisdom, behind and leads legions of winged servants to reinforce the position of the Vaati. The Blood War begins.

--After centuries of isolation, the yugoloths offer themselves to the warring sides as mercenaries. They bring contracts written on the skins of the dead, which are more binding to others than themselves. This marks the first time the yugoloths are involved in the Blood War, as well as the first time the yugoloths betray their employers.

--The Prime Material becomes its own separate plane. At the same time, the forces of Fire and Earth gain extreme dominance over Water and Air on the Inner Planes; Air and Water are nearly annihilated, as are the aboleth. What remains of Air is almost entirely Paraelemental Smoke.

--Some of the obyriths distinguish themselves above the others of their kind, becoming the first Lords of the Abyss. Some of them still exist: Obox-Ob, Pale Night, Ugudenk, Dagon, and Pazuzu. Many more are forgotten today: Veshvoriak, Vroth-Khun, Ubothar, Asima, Areex, Cabiri, and countless others.

--Among the forces of Law, many generals of the war distinguish themselves similarly, including Darbos, Emoniel, Penader, Uriel, Icosiol, Dispater, Gargauth, and Qadeej, although they are not yet attached to a single Outer Plane. The greatest general of Law is Aeshma, who is now called Asmodeus.

--Air begins to bounce back, and Water begins to amass huge victories, though fire still dominates. As a result, massive amounts of water appear on many prime worlds.

--The first indigenous lifeforms (microbes) are spawned on the Prime in thermal vents (black smokers).

--Air makes more strides, but is still dominated by Earth and Smoke. Nonetheless, the powers and quasipowers of Air manage to beat Smoke, taking half of the land it stole from Air. As a result, the sun shines on many prime worlds, providing the microbes with a new energy source: photosynthesis.

--Multicellular lifeforms arise on the Prime.

--Water and Air make massive strides; Air and Earth reach an equilibrium while Water dominates Fire. As a result, most prime worlds become dominated by oceans.

--Arthropods and plants arise on the Prime.

--The greatest leader among the obyriths becomes the Queen of Chaos, who cows or destroys most of her rivals under her banner. She also recruits many slaadi and other beings of Limbo.

--A primordial deity of vegetation causes the first multi-prime mass extinction event when he creates vascular land plants on many prime worlds. This extinction event is an analogue of the Late Devonian Extinction Event.

--Initially, the balance of the war swings wildly between the forces of Chaos and those of Law. Whole sections of the Outer and Inner Planes fall under the control of one side or the other every few years, only to return to the control of the other side a few years later.

--Pre-Cambrian Explosion analogue; flumph, oozes, ropers, and later on-- sentient arthropod, cephalopod, cnidarian, *that's anemones, corals, and jellyfish*, echinoderm, *that's starfish, urchins, and some sea cucumbers*, and fish species emerge *including a race of anthropomorphous trilobites*. The Aboleth Empire rises.

--As the war progresses, the war swings less dramatically. Key developments put large parts of the multiverse under the thumb of one side or the other, seemingly permanently. At the same time, the numbers on both sides dwindle, as they do not have any quick method of reproduction.

--Asmodeus is troubled by the absolute, maddening, anarchic, wicked depravity of the Obyriths, and hatred begins to grow in his heart. Convinced of the absolute direness of the situation, Asmodeus dedicates himself to the Obyrith's destruction, even if it endangers his soul. As he witnesses more depravity, and with the weight of being Law's and Good's champion weighing on his mind, he decides that the only way to destroy the Obyrith is to think like one, and forces himself to predict their seemingly incomprehensible behavior by attempting to envision the most evil and offensive action possible in any given situation, much to his own disgust.

--Gaea and her Titan children, fed up with Uranus's cruelty, hatch a plan to depose him. This results in the Protogenomachy-- a brutal war between the Protogenoi of the Outer Planes and the Titans. With Gaea and Eris on their side, the Titans win, and remove nearly all of Uranus's divine power. The Titans usurp the Protogenoi empire, deposing or demoting more than half of them, with the remainder holding their position for the time being, albeit less organized without their leader. This results in a wild swing towards chaos and away from neutrality. Combined with the Pre-Cambrian explosion analogue, this creates a disaster on the inner planes when the Positive and Negative Energy Planes, previously isolated (but very large) demiplanes infiltrating into the Inner Cosmology, become coterminous with the Elemental Planes. Whether it was the chaos of the Protogenomachy or the infiltration of the energy planes, the end result was that Elemental Earth and Elemental Fire switched places, and the connection between the Elemental and Energy planes resulted in formation of the 8 quasielemental planes.

--This has a devastating effect on the Prime, where many prime worlds become cold and dry; Pangaea forms, reducing the amount of most fertile land *shallow seas and coastal land*. Much of the land becomes inaccessible to the aboleth, who eventually design a new type of slave race capable of living its entire life on dry land-- the amniote. The larger species new races will also serve as hosts for the younger, smaller aboleth *though the parasitization process is painful and ultimately fatal*.

--A few colonies of the two most successful amniote slave races, the beast-like Chroch'chikaat and the lizard-like Chroch'hochaat, flee their homelands for the great interior region of their prime worlds. There they spend the next several centuries struggling to survive in an increasingly aridifying mountain environment. Also during this time, the land begins to warm, but it continues to dry out.

--These mountain dwelling amniote races petition the cosmos for help. Despite no answer, continue to appeal to the cosmos. As a result, over a period of several centuries, the first deities are born from the Astral, though these deities were radically different than those of today.

--Petitioners begin to arrive on the Outer Planes.

--Blessed by the gods, the amniotes can now focus on a plan to defeat the aboleth. After a couple centuries, they return to their homelands, contacting the rebels of all the aboleth's other slave races, informing them of their plans, sharing their technology, and spreading religion. The aboleth gain word of the amniote colonies' return and pursue them, but the colonists flee back into the interior.

--More and more petitioners arrive on the primordial outer planes, now mostly formed. Unfortunately, the Lawful Evil petitioners end up on Proto-Mechanus and Proto-Heaven by default, which the gods find distressing.

--Now blessed by the gods, many of the rebel slave colonies strike back against the aboleth, who are unprepared to deal with divine magic and divine psionics. Now and then the amniotes return to the seas to join them in battle. The aboleth begin to lose some of their lands. For the next few centuries, the war between the aboleth and their slaves swings back and forth, though few major strides are made by either side.

--During this period, both sides (of the Law/Chaos war) explore the planes more thoroughly, invading and dominating many other regions.
The Queen of Chaos recruits beings of the Inner Planes such as Ogremoch, Bwimb, Imix, and Olhydra, and she incites the efreet to rebel against the djinn who act as faithful servants of the Wind Dukes. Many of the leaders and forces of the Inner Planes who join the side of Chaos presumably do so to bargain for the Obyriths' mercy come time when they conquer the Multiverse.

--Early into the Law-Chaos war, Pazuzu and his army embark into the Elemental Plane of Air, where Yan-C-Bin overhears him claiming the title of "Lord of Evil Aerial Creatures". Outraged, the archomental accosts him, and an argument ensues, quickly degrading into violence. It results in a draw, but cements Yan-C-Bin's hatred for the Obyrith and gives him further motive to side with Law.

--An Obyrith Lord of cold (anyone know of a good name?) makes an attempt to assassinate Cryonax, in the hopes of supplanting him and establishing a foothold on the Inner Planes close to the Wind Dukes' base of operations. His attempt fails, but does not go unnoticed by the Bleak Monarch. Combined with their earlier invasion of "his" realm and the archomental's general distaste for their nature, Cryonax becomes embittered towards the entire Obyrith race and swears to annihilate them. As a result, he becomes an ally of the Wind Dukes.

--The Archomentals Yan-C-Bin, Bristia Pel, Ben-Hadar, Cryonax, Vesvolch, and Chan join the forces of Law along with the mephit lords Chilimba and Ekhak. Chan quits when she discovers that Yan-C-Bin is involved. The vaati also gain some limited aid from the Modrons.

--By this time many prime worlds have become very hot and dry, with much seismic activity as fire and earth continue to gain dominance, placing even more stress on the aboleth. At long last, the slave races see their chance to strike. In an unlikely alliance, every single slave race joins forces to strike against the aboleth, overwhelming them and finally bringing an end to the Aboleth Empires.

--The alliance between the slave races quickly crumbles, but aboleth might is too far decimated to take advantage of this, and they find no allies among their former slaves, who have neither forgiven nor forgotten their cruelty.
The aboleth are forced to retreat to the subterranenan world to regroup, but only find solace from the climate.
Never again will the aboleth rule the lands or the seas-- the age of the aboleth has finally come to an end.
From this point onward, on many prime worlds, the vertebrates, in general, dominate the seas while the amniotes alone dominate the land.

--A few of the Beings of Primal Law grow impatient with what they view to be the growing evil of Asmodeus, believing him to have been almost as corrupt as the forces he opposes. They send an army of millions of archons and angelic beings to end the war themselves.

--In the future, the celestials decide to only battle their diametric opposites. The Lawful Good celestials fight only the creatures of the Abyss, and the Chaotic Good ones fight only the creatures of Baator. Because of this, the Queen of Chaos gains a tenuous alliance with the Eladrin Queen of the Stars, whose people fight primarily on the Material Plane against the more corrupt forces of Law.

--After a few small groups of celestials attempt in vain to assassinate Asmodeus for his evil, something unprecedented happens: Asmodeus brokers a peace accord with the Queen of Chaos, and both armies turn on the celestial forces, annihilating them. Within a week, the celestials turn back. Only 3000 are said to survive. Asmodeus continues the alliance for only a short time thereafter to gather more intelligence on the Obyrith and Queen of Chaos. When the forces of Law and Good confront Asmodeus with his crimes, he slyly responds that he merely took out the "misguided" celestials who attacked him first (which was a lie-- only a minority attacked him, and his true motivation for slaughtering the celestials was his view that their misguided tactics jeopardized Law's side in the war.)

--Both sides give their members the task of recording information. The arcanaloths are said to write the only honest histories, seeing how they check and double-check each others' work. Unfortunately, their records, which begin during this period, are all but inaccessible in the Tower Arcane in Gehenna.

--It's only now that the feuding forces interact with the gods, though they've been around for what seems like forever. One or two gods of Chaos side with the obyriths, and the forces of Chaos seem almost unstoppable. Soon, powers across the planes choose sides.

--The Protogenoi and Titans take sides in the war-- the Protogenoi side with law, fearing the destabilizing effect an Obyrith invasion could pose to balance, while the Titans side with Chaos, hoping to finally tip the scales of the Protogenomachy in their favor. Up until this point, the Protogenomachy has not been nearly as fierce as it was before Uranos's destruction, and has resulted in a continued draw.

--A powerful god of Chaos begins to wither away. The other deities feel their essences start to dwindle. They stop involving themselves in the War so blatantly, interfering only through their proxies. Of course, a number of gods of war and destruction continue to dirty their hands in the fighting.

--The Great Mother cements an alliance with the Queen of Chaos, mating with obyriths and their creations to produce many-eyed fiendish offspring that are used in the battles.

--The Mask of the Pit strategy involves obyriths disguising themselves as minions of Law, although this fails. One of the generals of Law - some say it was the pit fiend Bel, currently the Warlord of Avernus - executes his legendary Four-Cross, seeming to betray his own side, then the side of Chaos, then his own side, and finally betraying Chaos again.

--Asmodeus begins his infamous 66 year campaign in the Abyss. Pazuzu hounds him the entire time with sardonic, mocking, and sometimes tempting words, but always finds some way to avoid physical confrontation.

--The forces of chaos create a new and more insidious form of Obyrith which parasitizes Celestials and gains sustenance by converting their law and goodness to chaos and evil. With this new creature in their arsenal, the Obyrith begin what will later come to be great strides in the war, subjecting tens of thousands of celestials and even modrons to agonizing deaths while bolstering their forces.
Mid-way into his 66 year campaign, Asmodeus receives word that another unit was ambushed, and their general, along with many other celestials went MIA. Little does Asmodeus know that they have been dragged off to the first brood pit of the aforementioned parasitic Obyriths.
That general just so happens to be Asmodeus's closest friend, who he considers to be like a brother.

--5 months later, Pazuzu gives Asmodeus's best friend a potion to restore his consciousness and ambulation, then quickly frees him from the parasite's tendrils which bind him to the floor of the brood pit before the potion takes effect.
Eventually, the general finds Asmodeus and his army, and does his best (considering his condition) to inform Asmodeus about the new Obyrith as his swollen abdomen pulsates with the deadly brood. When Asmodeus uses his Dispel Evil or Cure Disease spell-like ability, the brood goes into death throes and bursts forth from its victim in a spray of gore before finally dying.

--Near the end of his 66 year campaign, Asmodeus stumbles into the largest brood pit at the time while pursuing Pazuzu. There he finds 500 celestials parasitized and in agony from the Obyrith brood. One in particular, now nearly a gray, purulent husk, stands out-- she is his long-time lover. As Asmodeus contemplates what to do for her (realizing that even with his power key, he is unable to use curative magic within the brood pit), she literally gives birth to the parasite; when it emerges, she screams in a final death throe of agony as her skin shrivels away, leaving nothing more than a gray, deflated husk. The mature brood immediately attacks Asmodeus, but when he raises his sword to deliver the finishing blow, it pleads for mercy in his beloved's voice, using the same words and syntax she used in life. Asmodeus musters his willpower to slay the brood just in time to defend himself from more than a dozen other newly emerged brood.
After attempts to free and remove fellow celestials from the brood pit causes the brood to erupt prematurely, Asmodeus comes to the realization that he cannot save a single one of his fellow celestials.
He is forced to slay them all with his own sword in order to free them from their torment, save what little is left of their souls, and destroy the brood growing inside of them.
After this event, Asmodeus swears to destroy the Obyrith race at any cost, knowing that his own soul will be corrupted in the process.

--The mephit lord of magma, Chilimba, convinced that the archomentals of good were not prosecuting the war with sufficient zeal, murders Bristia Pel with the aid of Ehkahk, and indirect aid of Vesvolch. Horrified at the deeds of the side he was supporting, Ben Hadar defects to the side of Chaos.
Chilimba's pitchfork instantaneously acquires sentience when it snuffs out Brista Pel's life, becoming Quaereim, The Traitor's Fork.

--At around the same time, an Ice Weird and Snow Weird approach Cryonax to warn him of the impending disaster involving Fire, Magma, and Smoke as a result of Brista Pel's destruction. However, they are seduced by his alignment-changing aura and end up as his loyal servants.

--Ehkahk, Vesvolch, and Chilimba attempt to annex Brista Pel's territory on Fire.

--Enraged, Imix repels the invasion, captures Brista Pel's territory, and then invades the territories of Ehkahk and Chilimba in an act of revenge. Vesvolch, the Prince of Evil Magma, is foolish enough to challenge Imix and is slain. As a result, many prime worlds become hotter and drier. Because of the methane deposits that have accumulated on the ocean bottoms of many prime worlds, this results in a nasty feedback loop. It culminates with the worst disaster in Prime history-- the Permian-Triassic extinction event analogue.

--During the capturing of Brista Pel's stronghold, Imix's minions notice peculiar behavior among Brista Pel's servants. Imix believes this a sign they are guarding a powerful artifact, and arrives to investigate. Instead, he discovers a young Zaaman Rul, who he manages to deduce is his own son. Zaaman Rul is taken to the Temple of Ultimate Consumption to be raised and corrupted by Imix.

--The remaining archomentals save Zaaman-Rul all take measures to destroy any evidence of Vesvolch's existence, fearing that the tyrant might one day be revived by cultists-- even Sunnis embarks in an interplanar sweep to wipe out any sign of his cult and former servants. In the power vacuum, Chilimba becomes the unofficial ruler of the Paraelemental Plane of Magma during a vicious war between the mephits and the paraelementals of that plane.

--The draw between the remaining 50%, scattered Protogenoi and Titans finally crumbles as the latter finally overtake the former in the climax of the Protogenomachy. From this point on, the reign of the Outer Planar protogenoi ends, and the Titans and scaled ones reign supreme. The protogenoi who remained behind on the Inner Planes during the schism are unaffected, as they are not targets for the Titans' wrath.

--After several millenia, life on the Prime worlds begin to recover, with the rise of the dinosaurs, lizardfolk, aaracokra, and Eodraco (the ancestors of true dragons).

--After millennia of bitter fighting, the two sides discover a use for the souls of the mortal dead. The obyriths create the manes and other subordinate races, transforming them into the first tanar'ri. The vast breeding pits of the sibriex obyriths writhe with nascent life, and every generation brings new innovation and depravity.

--The Baatorians create the first nupperibos to be borne from petitioners (as opposed to spontaneous creation and sexual reproduction). These are carefully promoted into higher castes as they merit it. Nonetheless, many lawful evil petitioners continue to end up on Mechanus, Arcadia, and Celestia.

-- -9,998,500DR (approx) From this point on, the Material Plane becomes a crucial part of the War. The Wind Dukes secure many worlds for their Baatorian allies, while the Queen of Chaos takes many others.
During this time, Turaglas, the first or second Tanar'ri lord, is created "a thousand times 1000 years ago."

--The vaati, who - based in the Inner Planes - are unable to gain enough petitioners to create enough replacement warriors, continue to decline.
It was after this that the Queen of Chaos takes the most powerful of the tanar'ri, Miska the Wolf-Spider, as her consort, destroying Obox-Ob and naming Miska the Prince of Demons in his place. This brilliant combination tips the conflict against Law.

--Somewhere around this time, the forces of Law and Chaos discover the City of Doors, which seems to be the perfect launch pad for their armies. The problem is that an entity known even then as the Lady of Pain seems to have some sort of problem with her city being used this way. Some say the Lady was a renegade obyrith high-up who fled to Sigil to protect herself against the rage of the Queen of Chaos. Others say she was a General of Law. She doesn't mind lesser beings in her city, and she tolerates greater ones, but if they step out of line she doesn't hesitate to destroy them. That doesn't stop the forces of Law and Chaos from invading the city time and time again, sacrificing thousands to her bladed shadow in an attempt to get closer to the secret of the Lady's power.

--A group of unknown beings pledge themselves to the slaad lord Ygorl in an attempt to gain refuge from the tyranny of the Wind Dukes. With Ygorl's help, they create the demiplane that is later known as the Black Abyss.

--90,000 square miles of wasteland between two tributaries of the River Styx, known as the "Field of Nettles", becomes a major battlefield of the war. Rare is the year when piles of millions of bodies don't build up in the disease-strewn wastes. It is here where Ogremoch and Yan-C-Bin wage their famous battle against one another. However, Ogremoch is unable to hit the flighty Yan-C-Bin, while Yan-C-Bin is unable to damage Ogremoch's powerful body, so the two lose interest in one another and go their separate ways. A short time later, Ogremoch learns of the existence of Sunnis.

--DR -36,000: (approx) The creator god of the giants, Annam, is thought to have been born from the forces of Law and Chaos, or to have come to Toril at some point during this range of years. On an unnamed sky goddess, he fathers most of the giantish pantheon.

--DR -35,000 (approx) The Sarrukh, a Faerunian reptilian progenitor race, rise in Orkoth, south of modern day Mulhorand. Their fecundity forces them to expand rapidly across Faerun in the span of a few decades.

--DR -34,800 (approx) The Sarrukh create the various scaled races-- nagas, pterafolk, troglodytes-- and by combining scaled blood with the blood of the cave-dwelling ancestors of modern humans, the Yuan-Ti.

--DR -34,000: (approx) The Seldarine takes control of planar territory formerly under the control of the giant pantheon, founding the realm of Arvandor. Most of the giants, save peaceful Iallanis, are driven from Arborea into Ysgard.

-- DR -33,500 The Mhairshaulk Empire collapses, marking the end of the reign of the Sarrukh on Toril. Toril is thereupon ruled by the Batrachi, a Torilian amphibious progenitor tace.

-- DR -32,000 (approx) As the Obyrith brood continue to multiply, the loss of celestials, modrons, and innevitables in this way weakens the very planes of Law and Good, while bolstering the Abyss. The Eladrins can barely maintain the farce of alliance with the Obyrith when they witness such cruel atrocities, their souls crying out to avenge the thousands of victims to the cruel brood. The Obyriths nearly catch them in an act of treachery when they turn a blind eye to the forces of law storming the largest brood pit and mercifully laying waste to host and parasite alike.

--DR -31000 (approx) Eons of conflict finally shudder to a climax on the Material Plane world of Oerth. In the shadow of a great volcano called White Plume Mountain, in an area known as the "Fields of Pesh", Miska the Wolf-Spider fell in battle with the Wind Dukes and their allies. Miska is imprisoned in Agathion, the fourth layer of Pandemonium, by the Rod of Seven Parts.
In the middle of this conflict, Ogremoch and Sunnis encounterd one another for the first time, and the Fields of Pesh were rended, shattered, and split by their struggle. In the end, the battle was a draw, as both combatants nearly kill each other. Shattered into pieces, both archomentals returned to their strongholds on the Elemental Plane of Earth. It would be centuries before their wounds would heal and their sundered appendages would reform.

--DR -31000 (approx) However, the Vaati race is made virtually extinct by this battle and the long attrition that led up to it. It was a final, desperate use of all their remaining resources, and though it proved effective, the Vaati are never again an important planar race. The few remaining Vaati retreat to the Vale of Aaqa, dispatching only a few wanderers to ensure that Miska remains bound.

--DR -31000 (approx) Back on the Plain of Infinite Portals, the Obyrith alliance fractures, and the Queen of Chaos retreats to the Steaming Fen in the lower depths of the Abyss. Sensing weakness, the Queen's former allies turn on her. The Queen of Stars sends legions of ghaele knights to launch a devastating raid against the Plain of Infinite Portals-- the multiple millenia long alliance between them and the Obyrith revealed to be little more than a long-drawn act of espionage, intended solely to acquire intelligence. The Obyriths and their demonic thralls die in the thousands. For this moment the treacherous tanar'ri, led in part by Demogorgon and secretly bolstered (albeit indirectly) by the Obyrith traitors Pale Night and Pazuzu, explode in open revolt against their cruel masters.
The Eladrin and other opportunistic enemies of the fiends single out the Obyrith as the targets of their wrath, to the point of ignoring Tanar'ri hordes who do not engage them. The Tanar'ri, likewise, focus their hatred on their cruel masters to the point of ignoring the good aligned intruders who they find so abominable. Even the Yugoloths turn en-masse on the Obyrith to the point of violating their contracts after realizing that the millenia of unspeakable cruelty by the Obyrith have created enemies on all sides who now seek their vengeance. Instead, the loths favor the Tanar'ri, recognizing their less parasitic and more alluring traits as more favorable to the spread of evil and maintaining the balance between law and chaos.

--DR -3100 (approx) Asmodeus petitions the other Primal Beings of Lawful Good. He reminds them that mortal souls have begun interfering with their contemplations, and offers to set up a place on the Plane of Baator to issue corrective measures. The other Beings agree, and the Pact Primeval is signed.

--Baator becomes a place of horrific torments, the fine print in the contract allowing Asmodeus and his minions to gain great power from the suffering they inflict.

--DR -31000 (approx) A handfull of Obyrith survive either by allying with the Tanar'ri, resorting to bribery, or going into hiding.

--The Obyrith domination on the Abyss ends. From here on, the tanar'ri are the dominant race on that plane. With the collapse of both the Obyrith-Eladrin-Slaad alliance and the Vaati-Baatorian-Archon-Angel-Guardinal-Modron-Inevitable alliance, the war between Law and Chaos awkwardly stalemates, its violence mostly limited to the Lower Planes. The archomentals and genies refuse to answer to either faction, although wars between chaotic and lawful elementals continue among themselves. With the collapse of the Vaati empire, the archomentals are now held back solely by the Elemental Lords. Innumerable land-grabs and wars break out.
The slaadi refuse to ally with the tanar'ri, and indeed many of them aided the Eladrins in their purge of the Obyriths. Many still kill Baatezu out of habit, but only as independent agents. The Modrons continue to fight in the Blood War, but no longer as allies of the Baatezu.

--DR -31000 (approx) The culmination of the war and its immediate aftereffects results in the disastrous Cretaceous–Tertiary extinction event analogue, which wipes out most of the dinosaurs. Air is almost completely overtaken by Paraelemental Smoke, killing off even more species, who die either from impure air or the lack of sunlight. This includes many plant species, photoplankton, the colonial corals, and marine organisms which feed on them.
On Abeir-Toril, powerful Batrachi magic prevents this event from having a disastrous effect on Abeir-Toril, but just barely.

--DR -30998 (approx) Demons and devils continue to destroy each other in the Blood War, however, which is still a major source of conflict throughout the planes.

--DR -30997 (approx) Threatened by Smoke's encroachment to becoming a fully fledged Elemental Plane and the demotion of Air to a mere Paraelemental plane, even Yan-C-Bin and Chan forge an unlikely alliance in their desperation. Around the same time, Istishia forges a powerful artifact which might finally be capable of quenching the fires of Fire and Magma. Over time, the artifact switches hands between each Archomental of Water, Ice, and Air, until finally being claimed by Akadi-- each being further hones the artifact, making it more powerful. This artifact has the desired effect-- Water and Air finally gain dominance over Earth and Fire after so many millenia. This snuffs out the embers still burning across the surfaces of so many Prime worlds even 3 years later-- the one thing preventing these worlds from cooling due to the blocked sun. This combined with the culmination of the Law/Chaos war proves far too much for the Batrachi's planetary wards, and results in the collision of the Tearfall. The Batrachi empire collapses, while the empire of the Aearee, a Torilian avian progenitor race, rises.

--DR -30995 (approx) Akadi, Yan-C-Bin, and Chan also get their wish, and Smoke is beaten even further back than it was before the K-T event. Chan and Yan-C-Bin cancel their treaty.

--DR -30995 (approx) The cooling of the oceans leads to the extinction of the ammonites, belemnites, inoceramus, and the reef-building clams. From this point onward, the aaracokra go into decline on Abeir-Toril, and most sub-races of lizardfolk go extinct.

--DR -30900 (approx) Cryonax begins to conquer The Precipice (the border region between Core Ice and Air), declaring war on the Qorrash Genies, whose civilization was dealt a major blow by the disappearance of the Vaati. Gradually, Cryonax makes headway against the Qorrash, driving them off the surface of the Precipice. More and more Qorrash genies retreat to the skybergs, Core Ice, or into hidden (often via illusion) mountain and subterranean caves.

--DR -30900 (approx) With the Wind Dukes out of the way, the Baatezu exploit another loophole in their contract with the Primordial Beings of Law to tempt mortals into lawful evil so that they can legally torment them and use them as new recruits. The Tanar'ri respond with their own breeds of tempters. Both groups teach mortals the magic to summon them and foster cults of mortals who worship them as gods. Half-fiends and eventually tieflings begin appearing in greater and greater numbers. Entire societies are manipulated like puppets.

--DR -30900 (approx) Inspired in part by the Celestials and no longer oppressed by the Vaati, mortal champions begin to appear, fighting back against the encroachments of evil. Fiends begin to realize that mortals can be more than the mere insects they imagined them to be.

--DR -30900 (approx) Zaaman Rul witnesses his father's cruelty first-hand.

--DR -30600 (approx) The two Weirds deliver a cryptic prophecy to Cryonax about about future aquisition of a powerful weapon.

--DR -30508: (approx) Annam marries Othea, a mountain goddess of Toril.

--DR -30507: (approx) Othea gives birth to Lanaxis, father of the Titans, eldest son of Othea & Annam

--DR -30506: (approx) Othea gives birth to Vilmos, father of the Storm Giants, son of Othea & Annam

--DR -30505: (approx) Othea gives birth to Nicias, father of the Cloud Giants, son of Othea & Annam

--DR -30504: (approx) Othea gives birth to Masud, father of the Fire Giants, son of Othea & Annam

--DR -30503: (approx) Othea gives birth to Ottar, father of the Frost Giants, son of Othea & Annam

--DR -30502: (approx) Othea gives birth to Obadai, father of the Stone Giants, son of Othea & Annam

--DR -30501: (approx) Othea gives birth to Ruk, father of the Hill Giants, son of Othea & Annam

--DR -30500: (approx) Othea gives birth to Arno/Julian, father of the Ettins, son of Othea & Annam

--DR -30500: (approx) Life on the Prime worlds begins to recover from the KT event analogue.

--DR -30300: (approx) Zaaman Rul, now an adolescent, experiences his father's brutality first-hand during several instances in which he tries to protect servants and innocents from Imix's wrath. Imix's frustration over his son intensifies.

--DR -30000: (approx) Fall of the Aeree empires.

--DR -30000: (approx) After becoming lost in a snowstorm, one of Cryonax's patrols enters a clearing where they discover an abandoned, newly born half paraelemental gen. They present her to Cryonax, who adds her to his "specimen collection". Cryonax gives her the name "Frigidora", and entrusts her to a Frost Giantess widow to tend to her "fleshling" needs until she reaches an age in which she can be educated.

--DR -30000 Fall of the Aeree empires. Dragons and giants emerge as the rulers of the world. Araushnee is banished from the Seldarine, becoming the spider-demon Lolth.

--DR -30000: (approx) From this point on, the history of the Blood War is more exhaustively detailed, as mortals obsessively chronicle their interactions with the fiends and the secrets they learn from them. Although much of what they learn is lies, the sum total of their knowledge is a reasonably accurate picture of fiendish affairs.

--DR -30000: (approx) After the tension between Zaaman Rul and Imix reaches its climax, Imix realizes that his son can never be converted into a loyal servant of elemental evil. As a result, Imix disowns his son and kicks him out of the Plain of Burnt Dreams (Imix's territory).

--DR -30,000: (approx) The War of the Seldarine begins. Araushnee is cast down into the Demonweb Pits, where she slowly transforms into the demon goddess Lolth.

--DR -30000: (approx) Malkizid the solar is branded a traitor and cast into Baator.

--DR -30000: (approx) Zaaman Rul wanders Fire and returns to the region once controlled by his mother. There, Zaaman Rul rallies the remaining former servants of Brista Pel and defies Imix. However, neither archomental is willing to actually slay the other-- Zaaman Rul out of sentimentalness, and Imix out of arrogance (e.g. "doesnt' deserve the privelage of dying by my hand!")

--DR -29950: (approx) Chan learns of the relationship between Zaaman Rul and Imix and decides to act as a surrogate mother for the still adolescent Zaaman Rul.

--DR -29,900: (approx) Cryonax appoints the now nearly mature Frigidora as his herald and top ranking general.

--DR -29500: (approx) The succubi of the Abyss war with one another for dominance. A few high-ups eventually establish themselves as lords of various parts of the plane.

--DR -29500: (approx) Dragons and giants begin warring. The Dragonfall War begins between the followers of Bahamut and Tiamat.

--DR -29500: (approx) Zaaman Rul learns of the love-hate relationship between Imix and Brista Pel, something which neither Imix nor Brista Pel ever spoke to him of. Many of the servants believe that it was Imix's army which murdered Brista Pel. Zaaman Rul also becomes convinced of this, vows revenge, storming the Temple of Ultimate Consumption. When Imix emerges, Zaaman Rul makes his accusation and vows to avenge his mother, despite Imix's insistence that it was Ehkahk and Chilimba who slew his mother. The fight ends in a draw, but begins the bitter war of annihilation between Imix and Zaaman Rul. Henceforth, both Archomentals refuse to aknowledge each other as flame relatives, and the knowledge of this among the citizens of fire fades.

--DR -28,000 (approx) The Colossal Kingdom reaches its height on Toril

--DR -26000: (approx) Othea has an affair with Vaprak and bears the progenitor of the Ogre race.

--DR -25500: (approx) Othea gives birth to Dunmore, father of the Wood Giants, last son of Othea by Ulutiu. Othea and Ulutiu were also the parents of the firbolgs, verbeegs, and fomorians

--??? The illithid empire expands so far that the Blood War pauses for one of only three recorded times in all of history, the various Lords and generals worrying that the mind flayers will seize control of even the Outer Planes in their cold, premeditated conquest.
The rebellion of Gith eventually puts the fears of the various lords and generals to rest, at least for now. The Blood War resumes.

--DR -25,000: (approx) What remains of the Giant Kingdom of Ostoria reaches a truce with Dragonkind. The reign of Giants comes to an end.

--DR -24,500: (approx) The Elder Elves appear on Toril, Oerth, and other prime worlds after escaping the "Plane of Faerie".

--DR -24,000: (approx) Yuan-Ti civilization collapses after centuries of assault from dragonkind. At around the same time, the reign of dragons finally comes to an end in the face of elven high magic.

--DR -18,000: (approx) Centuries of planar research and Elven High Magic on Oerth results in a disaster known as the Vast Gate Incident. In an attempt to create portals to uncharted "planes between the planes", the Elder Elves inadvertently open a rift in the fabric of reality into a multiverse known as the Far-Realm. Inimical energies, ideas, and creatures poured out of the gate, and the Elder Elves struggled to undo the damage and avoid madness at the same time. The situation became more dire when the Elder Evil known as Father Llymic emerged from the gate.
In the end, they were largely successful, but the event left a scar in that part of reality's fabric, and elven civilization on Oerth collapsed after so many high mages were rendered insane.

--DR -18,000: (approx) In the years following the Vast Gate incident, the Illythari clan on Toril and Oerth begin to turn to forbidden and nearly forgotten gods. On Toril they begin to venerate Ghaunadaur, while on Oerth they begin to venerate the Elder Elemental Eye, an aspect of Tharizdun. Such practices have a corrupting effect on their culture.

--DR -4600: (approx) The 13 children of Temulea create a celestial object called the Daegir, which is used to imprison several noble/ascended Mistji. Their essence is slowly siphoned and combined with the souls of elves to create the Sulwynaari race, a subrace of elvenkind.

--DR -3900: (approx) The Sulwynaari begin to explore the planes extensively. A colony is established in the Quasielemental Plane of Mineral as cultists and servants of the Prince of Quasielemental Neutral Mineral, Crystalle.

--DR -3400 (approx): Temulea learns of his childrens' betrayal in the creation of the Sulwynaari, and goes into a rage across the Outlands, its effects reverberating across Violetspace. Only Krug, the god of war, is foolish enough to challenge his father, and is slain. His blood is scattered across Avadnu, which would eventually lead to the creation of the Skarren race.
Temulea's other children cast the Daegir to Avadnu in an attempt to distract Temulea while they escape to take temporary refuge in the divine realms of allies. However, Morindalien, one of the twin moon gods, is unable to escape the Daegir's path in time, and is slain, his body sundered. The children of Avadnu rush to acquire the fragments of the Daegir, which still contain much power.
In the meantime, Temulea suffers a nervous breakdown and goes into an eternal slumber to escape from his pain. His alignment also changes from CN to CE.

--DR -3399 (approx): The War of the Daegir begins when a Zeidian warlord, known today only as "Kar’lil-arak" (roughly "the Lost") dares to gaze at the Daegir as it falls to Avadnu. This warps him and causes him to be consumed by insatiable desire for the Daegir. However, the Sulwynaari beat him to it. Frustrated and not deterred, Kar’lil-arak seeks forbidden power, and this married with his dark lusts transformed him into a threneghul when his physical body was destroyed in a fierce battle involving a combination of Sulwynaari, Mistji, Zeidian, and Khasep-Sa might. The war drags on for many years.

--DR -3390 (approx): The War of the Daegir is interrupted when strange creatures with maddening forms emerge from Avadnu's oceans and begin to destroy and corrupt everything they see. Though slumbering and slowly dying on the Astral, Temulea continues to exert his will on his children and the inhabitants of Violetspace. His nightmares created The Void, a slightly Far-Realm-esque demiplane full of Far-Realm-like Xxyth, a race created by Temulea to undo his creation entirely. As the Xxyth and other voidspawn go to war with the Sulwynaari, the Time of Chaos begins.
The dreaded threneghul warlord continues to seek the Daegir, but becomes preoccupied with the hordes of voidspawn just asking to be slaughtered.
The Sulwynaari manage to rally all sentient races of Avadnu to their aid in annihilating the Voidspawn, all except for the Ngakoi, that is.

--DR -3374 (approx): The Ngakoi, realizing that there can be neither escape from nor mediation with the Voidspawn, finally join forces with the Sulwynaari. Unfortunately, the Voidspawn just keep coming, and the children of Avadnu are in a losing position as their resources begin to exhaust. At the same time, Ptah and Celestian decide that Violetspace must be sacrificed in order to save the rest of the multiverse and prevent the Voidspawn's spread-- the crystal sphere must be condemned and sealed away forever. Irunean, now representing the Avadnian pantheon, pleads with them to reconsider.

--DR -3368 (approx): The Sulwynaari finally use the largest shard of the Daegir, a major artifact known as the Ulwynaarl (or spirit-stone), against the Voidspawn. The Sidereite make of the artifact bestows it with phenomenal taint-annihilating powers. When it is used, all taint on Avadnu is instantaneously purified, and because taint is every bit of a Voidspawn's essence as evil is a Tanar'ri's essence, the artifact destroys all voidspawn on the planet. However, the gates are still open, and more voidspawn flood out.
Less than a month later, Irunean comes to an agreement and concession with Ptah and Celestian. They will create a demiplane to separate Violetspace from the rest of the multiverse, and The Void from Violetspace. In addition, they will place a seal on The Void in order to close it. By combining their powers, they succeed in their goal, and the flood of voidspawn armies finally ceases on Avadnu. The races of Avadnu are able to wipe out nearly all the voidspawn remaining, though several manage to go into hiding. However, the seal on The Void is barely strong enough to hold, and the Time of Chaos takes a heavy toll on the children of Avadnu-- esp. the Sulwynaari, whose race falls into significant decline, and their domination of Avadnu ending. In addition, the prolongued wars bring a complete end to civilization for all races of Avadnu.

--DR 1450: Zaaman Rul and his army lays siege to Imix's territory of the Plain of Burnt Dreams. However, Zaaman Rul underestimates his foes; his army is decimated, and Asgeroth, Imix's herald and top ranking general, fatally wounds him. A phoenix who had been secretly watching Zaaman Rul for some time, comes and heals him. Zaaman Rul goes into hiding thereafter, as the Efreet destroyed his stronghold when they learned that the prince had been grievously wounded.

EXPANDED NOTES ON EVENTS
Below are less brief retellings of some of the events covered above.

The Amniotes and the Fall of the Aboleth Empire (prehistory)
A few colonies of two of the amniote slave races-- the reptilian Chroch'hochaat and the mammal-like Chroch'chikaat, flee their homelands for the great interior continental region of their homeworlds in a desperate attempt to escape their cruel masters. True to their plan, the aboleth are unable to follow them beyond one or two parasitized hosts.
In the interior mountains they spend the next several centuries struggling to survive in an increasingly aridifying environment, though they yearn for revenge and the chance to return to their homelands to free their kin.
Over the centuries, these Chroch'hochaat and Chroch'chikaat colonies petition the heavens, the mountains, the waters, even abstract concepts for help. They receive either no answer or inconclusive answers, but continue desperately to petition the cosmos for aid-- in their current situation there simply wasn't anything else they could do. Eventually, something miraculous happened-- they received an answer, from the first deities. Through the power of belief, these deities had been borne from the raw essence of the Astral plane itself. Of course, none of these deities were the ones we know today.
With their circumstances eased by the blessings of the gods, the Chroch'hochaat and Chroch'chikaat thrived. This allowed them to focus their efforts on a plan to overthrow the aboleth once and for all. After a few centuries of developing divine magical and psionic abilities, as well as honing their combat skills, the Chroch'hochaat and Chroch'chikaat return to their homelands, where they contact the rebel cells of the other slave races-- the flumph, the anguillians, the trilobite men, the coralites, etc. They spread religion, and hatch a complex plan to overthrow their cruel masters, despite that many of the races despise one another bitterly. Working together would simply be a small price to pay to destroy the cruel aboleth.
When the aboleth gain word that the fled amniote colonies have not only survived, but also returned, said colony descendants retreat back to the inlands for a time, being almost entirely unreachable by the aboleth. The aboleth send several hosts to deal with the problem, but the inland colonies have since learned how to recognize the hosts and neutralize the aboleth's powers.
A decade or so later, the rebel splinters of the slave races strike back against the aboleth in full force. The aboleth are unprepared to deal with divine magic and psionics, and suffer heavy losses. Just as the aboleth begin to turn the tides, the Chroch'hochaat and Chroch'chikaat colonies return to the seas to join the onslaught. The war drags on for several centuries, swinging back and forth between favoring the slaves and favoring the aboleth. Portions of the Chroch'hochaat and Chroch'chikaat colonies remain behind to continue hatching secret plans against the aboleth.
Eventually, the change in climate and the burden of a protracted war take their toll on the Aboleth Empires.
At long last, the slave races see their chance to strike. In an unlikely alliance, every single slave race joins forces to strike against the aboleth. Overwhelmed by the combination of divine magic, physical might, and environmental stress, the aboleth and their last empire finally collapses, and collapses utterly.
It's not long before the alliance between the slave races quickly crumbles, but the defeat of the aboleth is so extensive that they are unable to defeat any of their adversaries, who have not forgotten nor forgiven the aboleth's cruel treatment-- cruelty far beyond anything any of the slave races can match. The aboleth are forced to retreat to the subterranenan world to regroup... unfortunately, many of their former slave races await them there, as well. Never again will the aboleth rule the lands or the seas-- the age of the aboleth has finally come to an end.

Imix, Brista Pel, and Zaaman Rul (prehistory~ 30,500)
Not long after Imix was born, the Elemental Plane of Fire bore the archomental princess Brista Pel of Elemental Good Fire, to maintain the balance on the plane between good and evil. Imix learned of Brista Pel some time after he learned of Olhydra, who was of more pressing concern to him, but nonetheless, he also declared open war on the Fire Princess. At this point in time, the Obyrith civilization was only now realizing (and accepting) that there existed planes beyond theirs. The Baatorians were already beginning to explore adjacent planes.
Eventually, Imix and Brista Pel met in battle, and were amazed by one another's appearance. Brista Pel petitioned Imix to fight her alone, away from their armies so as to spare them from being burned by their Primal Energy (see Archomental template in Denizens of the Inner Planes). The misogynist Imix smugly agreed to this, but only because he planned to have his way with the princess. As it turned out however, the headstrong Brista Pel wasn't exactly unwilling to be subject to Imix's whims. What began as a fight to the death devolves into a consentual but angry sexual encounter.
The lovers would secretly meet many more times over the next several millenia, even though they were at war with one another.
Eventually, the Law-Chaos war erupted, and engulfed the entirety of the Inner Planes leaving both Brista Pel and Imix preoccupied. They would never see one another again, and unbeknownst to Imix, Brista Pel had conceived. She would go on to join the war in person once Zaaman Rul had reached the stage of medium-sized elemental.
Late into the Law-Chaos war, Chilimba the Mephit Lord becomes convinced that the archomentals of good were not prosecuting the war with sufficient zeal. With the aid of Ehkahk, he murders Brista Pel and attempts to frame the side of Chaos, but fails when Ben Hadar himself along with many of Imix's loyal minions witness the event.
Imix's minions make haste to report their findings to him. Though none of the minions present were aware of Imix's secret fling with the Princess of Elemental Good Fire, most of them took offense to seeing one of their own kind being taken out by lowly mephits of mere paraelements.
When Imix learns of Brista Pel's fate, he flies into a rage; Brista Pel was not just his lover, she was his property, and the Mephit Lords had shown him a great offense. Imix and his armies go on a rampage across the Paraelemental Planes associated with fire, annexing or destroying everything in his path-- Imix rallies every last minion not protecting his Temple of Ultimate Consumption and reassigns them to this task. Only a few dozen informants, spies, and scouts are left to their original tasks.
At the same time, Ben Hadar defects to the side of Chaos while Sunnis alone remains steadfast in her loyalty to the side of Law.
Chilimba and Ekhak waste no time and take the opportunity to lay siege to Brista Pel's stronghold. Imix's spies quickly inform him of this, and it is not long before he arrives to repel the invasion. Chilimba and Ehkahk manage to survive however, as they both flee before Imix can lay his eyes on either of them. After decimating the armies of Smoke and Magma, Imix assigns a small army to annex Brista Pel's stronghold-- rightfully property, in his mind, while he returns to the task of slaughtering every last entity of magma and smoke. Realizing they cannot beat Imix in his fury, Chilimba and Ekhak instead annex bordering areas of Air and Earth. All in all, it seems as though the Elemental Planes of Fire, Magma, and Smoke all expand greatly, crowding out the other Air and Water-based planes.
This siege on Brista Pel's stronghold continues for over a month, with Imix's army slowly gaining headway. They notice peculiar behavior among Brista Pel's servants-- they appear to be protecting a specific area at the very core of the stronghold at all costs. When messengers report this to Imix, he becomes exceedingly curious, believing the servants to be guarding a powerful artifact. He decides to return to Brista Pel's estate to investigate this for himself. On the way, he comes to realize how much weaker he has become-- in his fury he expended far too much of his power, though he remains incredibly powerful.
When he plows through the remaining defenses of Brista Pel's estate, he discovers a young flameling (equivalent to a 10-12 yo human in life cycle stage) cowering in a far corner of the room. Imix immediately realizes that the flameling is Brista Pel's son. He also recognizes that the flameling's elemental aura is intimately familiar, and realizes that the boy is his son as well. Amused, Imix decides to capture the flameling with the intent of molding him into a suitable minion of elemental evil. As his first act, Imix feigns compassion and informs Zaaman Rul of his mother's passing, a fact that the flameling had been unaware of as the servants had not yet been able to bring themselves to tell him. Imix further tells the lie that Brista Pel's servants had kept this information from Zaaman Rul for nefarious purposes.
As the millenia pass however, Zaaman Rul becomes distraught over the abuses he witnesses his father inflict upon his kinspeople, and uneasy with the physical and verbal abuse he suffers personally at his father's hands. In his later adolescence, Zaaman Rul can tolerate no more and intervenes several times while witnessing such. In each instance, Imix assaults him severely both physically and verbally. By this time, Imix's frustration with his son is nearing a boiling point-- even now, Zaaman Rul's alignment does not change in the presence of his father's aura, nor as a result of intensive indoctrination. Instead, Zaaman Rul has the audacity to defy Imix, even to the point of stepping between him and his victims.
The situation finally does boil over 300 years later when Zaaman Rul dares to raise his hand against the elemental prince. After ruthlessly beating him, Imix comes to realize that Zaaman Rul cannot be converted-- he has simply basked in his mother's good aura for far too long and was 'rescued' at to great of an age to be influenced by the Prince of Elemental Evil Fire's own aura. Disgusted and ashamed, Imix disowns his own son and exiles him from the Plain of Burnt Dreams. Zaaman Rul is kicked out of Imix's kingdom, beaten and alone.
For the next few years, Zaaman Rul wanders the Elemental Plane of Fire, eventually returning to the region formerly ruled by his mother. Disgusted by his father's behavior and rejected by him, Zaaman Rul vows to overthrow the Archomental and rallies the surviving former servants of Brista Pel.
This intensifies the rift between father and son, though neither is able to bring themselves to kill the other. Despite how truly evil and reprehensible he might be, and how much he personally had hurt Zaaman Rul, Imix was still his father. Imix, too, could not bring himself to kill his own son, no matter how audacious and defiant his behavior. Besides that, in his arrogance, Imix viewed that slaying his own son would be a form of aknowledgement-- aknowledgement of his son, aknowledgement of his prowess, and aknowledgement that he was a threat to Imix's regime-- none of which Imix had any intention of doing.
After a few decades, Chan learns of Zaaman Rul's lineage from a captured air grue. Despite her skepticism, the air princess approached the still adolescent Zaaman Rul and took him under her wing, acting as a surrogate mother of sorts.
A few centuries later, Zaaman Rul meets up with a long lost former servant of his mothers-- one of Brista Pel's personal retainers and confidonts, in fact. This servant fills Zaaman Rul in on the love-hate relationship between his parents, and reveals what she mistakes to be the truth-- it was Imix who killed his mother thousands of years ago. Zaaman Rul also becomes convinced of this-- after all, it makes perfect sense. He vows to avenge his mother's death, and with his army, he assaults Imix's stronghold. However, Imix's servants had been ordered not to kill Zaaman Rul, and they attempt in vain to convince him to leave. Eventually, Imix himself emerges to confront the young upstart. It is then that Zaaman Rul makes his accusation, and informs Imix of his vow. Greatly angered, Imix sets the boy straight that it was the mephit lords who slew his mother. Zaaman Rul refuses to believe his claims, and launches a few epithets at his father. Imix is both infuriated and amused. Infuriated at the accusations, infuriated that once again his black sheep of a son has defied him, yet amused by the vow. After all, this was the boy that could barely raise a hand against his own father to defend himself. Yet now he thinks that he can kill his own father? Laughable. Imix calls the boy's bluff, but is soon taken by surprise as Zaaman Rul attacks without hesitation. After both inflict several serious injuries upon one another, everything, in Imix's mind, changes. Not only his own son DARED to assuse him of killing Brista Pel, but he has the audacity to make an attempt on his own father's life. Imix shows no mercy, and promises to slay the yoing prince without hesitation, while in the meantime the armies of father and son continue to battle. In the end however, the duel ends in a draw, both archomentals fleeing after suffering severe injuries. Thus begins the bitter war of annihilation between Imix and Zaaman Rul, who both refuse henceforth to aknowledge one another as relatives. As a result, knowledge of this fact among the citizens of Fire fades.
Millenia later, Imix meets Asgeroth, who becomes his champion and is personally assigned with slaying Zaaman Rul. Imix will not grant Zaaman Rul the privelage of dying by his hand. He will not even be present to watch Zaaman Rul die when that time comes-- after all, that, too, is a privelage he does not deserve.

The Winter's Resurrection (approx DR -30997)
Threatened by Smoke's encroachment to becoming a fully fledged Elemental Plane and the demotion of Air to a Paraelemental plane, the desperate Yan-C-Bin and Chan make a temporary treaty, despite their hatred-- Chan cannot bear the impurity of smoke, while Yan-C-Bin cannot tolerate its heat. At the same time, Istishia, long frustrated with Fire's dominance ever since the late Permian analogue, crafts a powerful artifact from a large chunk of natural colorless eternal ice *the most valuable kind* which will douse the embers of Magma and Fire at long last. This artifact, which would come to be known as the "Winter's Resurrection", makes its way into the hands of Olhydra (aided by the prophecy of her Weirds) and then Ben Hadar, who both hone the artifact further.
As it is transported across Ice, Cryonax's army captures the caravan (after also receiving a prophecy from his Weirds) and makes his own adjustments to the Winter's Resurrection, making it even stronger still.
It makes its way into Air where Yan-C-Bin, then Chan, and then finally Akadi hone it further, allowing it to neutralize the toxicity of smoke, and making it even more powerful an artifact than the Rod of Seven Parts. When put to work, the Winter's Resurrection has the effect that Istishia, Olhydra, Ben Hadar, and Cryonax had desired-- Water and Paraelemental Ice gain dominance over the inner planes, once again, which snuffs out the embers still burning across the surfaces of so many Prime worlds even 3 years later-- the one thing preventing these worlds from cooling due to the blocked sun. This combined with the culmination of the Law/Chaos war proves far too much for the Batrachi's planetary wards, and results in the collision of the Tearfall. The Batrachi empire collapses, while the empire of the Aearee, a Torilian avian progenitor race, rises.
However, so densely packed with power was the Winter's Resurrection, that its physical form could scarcely contain such might. When Akadi used the orb, it shattered into 999 fragments and was scattered across the Inner Planes.

Vesvolch, the Forgotten Prince of Magma
When Tharizdun forced the Elder Elemental Eye (prior to fully absorbing it) to spawn the four princes of elemental evil, he also created two paraelemental lords to act as backups in case one of the initial four were slain. Cryonax covered Water and Air, while Vesvolch covered Fire and Earth. He was the youngest and weakest of the six, yet also the most hated-- and in some respects, the most feared, as he was a true bully.
In personality, Vesvolch suffered from explosive anger and was a very spiteful individual. Any records that somehow escaped destruction describe him of being envious of both Imix and Bista Pel. However, in reality Vesvolch was jealous only of Imix-- insanely so, while he wanted Brista Pel as his own personal plaything and slave. His jealousy was over the power and prestige that Imix enjoyed, the fact that, like Cryonax, he has been left out of the Eye's future plans, and also-- jealous over Brista Pel-- he was among the few in the multiverse aware of that relationship, due to his stalker-like behavior towards Bristel Pel, who had dared prior to her fling with Imix to spur the Magma prince's advances.
He, like Chilimba, the Mephit Lord of magma, sided with Law, though he did so only out of obsession for Brista Pel and hatred of Imix.
When he learned of Chilimba's and Ekhak's plot to advance the war, he wanted in. Unlike the two mephit lords however, he did not participate directly in Brista Pel's murder. Instead, he made sure that Cryonax and Yan-C-Bin, who were participating in the same battle, were suitably distracted. It was highly unlikely that either one would lift a finger to save the princess, but it wasn't a chance the plotters could take, no matter how remote.
Unfortunately, Vesvolch failed to take one thing into consideration-- Imix's spies were present, and witnessed the entire event-- they had even infiltrated all of the fire-dominant armies, including the magma prince's own.
When Imix learned of the mephit lords' and the Magma prince's heinous actions, he was enraged-- never before and never since has Imix ever been so furious.
Vesvolch, in his arrogance, believed that he, unlike his mephit lessers, could withstand Imix's abuse, which after all, would be divided between so many targets. Unfortunately, he never imagined just how truly enraged Imix would be.
Imix, in his fury, slaughtered the Prince of Paraelemental Magma, but at great cost to himself (between the Magma prince, the mephit lords, and everything else on Paraelemental Magma and Smoke, Imix used up most of his power and was greatly weakened, sitting out much of the remaining Law-Chaos war in order to recuperate)
Upon the Magma lord's death, the remaining five Princes of Elemental Evil, along with Ben-Hadar and Sunnis, worked separately to destroy any evidence that the prince ever existed. Imix did so out of pure vengeance, while Yan-C-Bin, Cryonax, Ben Hadar, and Sunnis sought to eliminate any chance that servants or cultists could one day resurrect him somehow. Ogremoch simply sought to ensure that a powerful rival could never return.

Fixed.
I'm not sure where to go from that point, though. Is it the Baatezu and Tanar'ri who discover that they can create more of themselves from petitioners, or the Obyrith and Baatorians?
Also, I don't know enough about Pale Night's spawning of several Tanar'ri. Did she do this as a means of rebelling against the Queen of Chaos? Or did she bear her children after the Law-Chaos war?

There's also a problem in that I think the aboleths are supposed to come into being AFTER the Law-Chaos war starts, yet I'm pretty sure the Archomentals are supposed to have been around for some time before it started. This creates a problem if we assume that the Blood Queen's brush against the border is the cause of the original Far Realm leak that brought Ghaunadaur and Tharizdun to the Multiverse.

Misc note: I have a scene where Frigidora chastises an upstart Icelord (before Cryonax imprisons him and devours his soul), claiming that Cryonax was born when the General of Gehenna was clad in a loincloth and painting on cavern walls with his hands (well, she would have articulated it better than that-- and no, she's not claiming that he was less evolved physically, merely that Yugoloth civilization was in the stone age. She is speaking to a mephit or paraelemental who is presumably a few thousand years old at most, who claims that he'd make a better ruler than Cryonax).

I think the next event though is to be Imix's and Brista Pel's relationship (and Zaaman Rul's conception)

Also, holy moley the Law-Chaos war is going to last for a long time. We're now still at the Pre-Cambrian explosion, and that thing's going to last until the K-T boundary (that's when the dinosaurs get wiped out) The Permian-Triassic extinction event will also be a direct result of the Law-Chaos war (likely when chaos gets the strongest and the Windduke empire begins to really break down, allowing Fire to subsume large parts of Air and Earth, which causes them to subsume parts of water. Actually, this could possibly have been a result of Imix's wrath on the planes of Ekhyk and Chilimba for the murder of Brista Pel.)

At least in Bruce Cordell's novels, they have no concept of themselves as individuals, and I tend to accept the notion from Ghostwalk that aberrations in general have no souls.

The Nagas and Ixichitl seem to have souls, though. Pretty sure the Elan and Synad do, as well. Then of course there's the flumph, which seems to merely be antediluvian (rather than alien)

Sp. Rip, I still need your input on the dragon-related timeline stuff (and titan and giant-related stuff)

The Planescape Monstrous Compendium Appendix III suggested, in the description of the wavefire, that there used to be a Paraelemental Plane of Steam between the elemental planes of Fire and Water. Between Earth and Air was the Paraelemental Plane of Dust. Long ago the inner planes reconfigured themselves so that the Paraelemental Plane of Steam became the Quasielemental Plane of Steam instead, a place of chill mists instead of boiling water (and the Paraelemental Plane of Dust became the Quasielemental Plane of Dust). This is why steam mephits share that plane with mist mephits, and why the wavefire (basically a boiling water elemental) lives in such a cool plane.
I don't see this event appearing on your timeline, but I think this would be a good place for it. Instead of smoke choking the sunlight from the worlds, steam could do the same thing.
Ah, yes I remember that, what was originally a bit of developer's humor by Gary Gygax (the whole thing is actually a reference to his original inner planar cosmology draft)

What is that event involving the Inner Planes from anyway, Hyena? About Fire and Earth getting dominance over Water and Air. Is that your fanon, or from some product? It sounds like the sort of thing I'd want to incorporate into my own timeline, and I'm curious if you've got any more info or a citation about it.

It's my fanon used to explain why extinction events and natural history among many prime worlds in D&D is so similar.
While, YES, we only know of a couple settings with such a similar timeline, the fact remains that the ecology is the same (with the dinosaurs being wiped out by an ice age bla bla, generally around the same time). It was an idea I came up with and the entire reason for this topic in the first place (initially, to see if my hypothesis correlated with the canon by looking at the approximate time the Law-Chaos war took place). In order for each prime world to have such similar ecologies, they must also have very similar natural histories-- meaning there had to be analogues to real-life extinction events. Obviously, Athas is an exception to this rule.
Not all the extinction events were Inner-Planar related of course. The first of the "Big 4" was the result of a primordial multi-sphere plant power's meddling. (technically probably falls under "elder evil" category, though it wouldn't necessarily be evil-aligned. At least, that's how I pictured it anyway-- the mass extinction was an accident, and the power/elder "evil" was merely naive or short-sighted or aloof in its meddling. Also, this explanation paves the way to alluding another reason why the ecologies are so similar across many Prime worlds.)
That said, now that I think about it, Father Lemic (Elder Evils) may well have caused the extinction of the dinosaurs on Oerth before it was imprisoned by the Elder Elves. Though, obviously, that would place the Elder Elves in existence (and highly advanced...!) at the end of the Law-Chaos war and during the reign of the dinosaurs.
Oh, for those not aware, Father Lemic's power is the ability to cover an entire prime world in glacial cold and pitch darkness (and insanity). He was one of the beings that escaped the Vast Gate during the experiment on Firestorm Peak by the Elder Elves.

I think I do remember him describing that earlier.
Just for the record, I'm female.

BTW, anyone have any idea when the Far Realm incident on Oerth was? I assume it was before the first Crown War on Toril. I wonder if there's any connection between that event and the rise of the Ghaunadaun cults? (which I think translates to the Elemental Eye cults on Oerth)