Epoch of Destruction
From Dragon Eye Atlas
The gap in time, the break in the world, the epoch of darkness, death and destruction. Known by many names, this period is deeply embedded in the oral histories of both elves and dwarves.
While different sources attribute different evil gods or other causes, it is known that this was a time of wars and terror. Even the very shape of the earth was affected by it, culminating in The Sinking of Pandongia.
The elves and dwarves were not the only races to appear upon Auseka. Aside from the many mythical races, one more humanoid race that survives till today began to make the continent theirs - the Orcs. They swept over the plains and into the forests, burning and slashing, and threatened elven forests as well as dwarven mines. For a long time they seemed an unstoppable force that was bound to sweep away all other races and come to dominate Auseka.
The Orc Wars woke another terror, one more cunning, more brutal and more complex. The dragonspawn, true dragons and the related lesser races, had always been present in the mountains, but as the orcs expanded and other races were driven before them, they saw these small creatures they had not cared much for so far pressing in towards their domains. The dragons answered with magic and fire, sweeping down over the forests and plains and taking revenge a thousand fold for each lair disturbed, and ten times more for each of their number wounded or slain. This sudden inferno managed what even an alliance of the civilized races had not accomplished: It stopped the orc expansion. By the dozens, orc war camps were burnt down and by the hundred thousand the greenskins destroyed.
Someone or something awoke an ancient god so old that he had been forgotten. The Nameless One as he is called in myths as even his name is not remembered by elves nor dwarves (nor any of the younger races, of course) had been sleeping or locked away for ages. When he awoke, he found the world not as he was used to it, and people of all races praying to new gods. His desire to return to his previous power sparked a war among gods and their followers - both mortal and supernatural. The skies were ablaze with magic energies, angels and demons joined battle as did the gods themselves.
In the end, the world itself was smashed apart in a cataclysm of magic that ended the gods presence. No longer would they walk among the mortal races. Since those days, the gods have remained in the heavens, speaking through prophets and acting through miracles. Whether this was by choice, by a kind of godly treaty, or because they no longer can is hotly (though cautiously for not angering any gods) discussed among those interested in arcane topics.
The cataclysm did not just end the gods' presence, it also smashed Auseka into pieces, sinking its central core into the grounds. As the ocean rushed in over the hot magma of the broken ground, it flooded cities and carried away entire civilizations. The thick clouds of the ocean waters being turned to steam as they met the inverse volcanoe where Pandongia had been changed the climate for decades.
All creatures suffered, with the great civilizations of the elves breaking down and the dwarves retreating underground.
The civilization of the centaurs was hit the hardest by the preceding events. Already badly damaged by the Gods Wars, the sinking drowned hundreds of thousands. Those that remained suffered under the conditions following and could never rebuild their civilization. They lingered on for a few hundred years, becoming more and more feral and breaking into smaller and smaller communities, until finally the centaurs were gone from this world.