The Seas of Arnesia
The War of the Burning Sky, the War-That-Broke-The-World. On one side, the dragonborn armies of Arkhosia; on the other, the tiefling-led legions of Bael Turath. A battle which began over borders, but turned into a war which lasted for 1,000 years.
When the war first started the Nine Divines took a great interest in who emerged victorious. They offered their boons, anointed champions, and even sent some of their own divine agents to intercede in the battle. But as the conflict raged on, one-by-one the gods withdrew their support- the battlefields of those days became god-forsaken wastes, too vast and terrible even for the gods.
Uncountable abominations were unleashed in that war: the Arkhosian Degradations; the Nightmare Child; the Horde of Travesties; the Could-Have-Been King with his armies of Meanwhiles and Never-Weres; the Memories of Xarak with its Thirty-Three Hidden Names of Man. It was only a matter of time before something truly horrific occurred. But no one could expect what followed.
In a single day and night, both Arkhosia and Bael Turath were wiped away. Entire armies perished beneath an unending torrent of white fire. Dovallith, the legendary port city of Arkhosia, crumbled to pieces and sank into the sea. And today a field of nothing but black dust stretches across the land which was once Anathaneum, the last capitol of Bael Turath.
So fearsome and horrible was the Scouring that the continent of Sithirus was ripped asunder, creating the new land of Oroth-Killean, and leaving a vast, storm-wracked ocean between them. The gods themselves withdrew from the world, and to this day they do not commune with their faithful half as often or fully as they did in ages long ago.
Such was the Scouring, the day that all the world wept.