Into the Wild West
The first great Human Empire, it became corrupt and repressive once infiltrated by the previously unheard of Tiefling race. It’s power was broken by an army of rebel freedom fighters who united with the Dragonborn of Arkhosia.
Bael Turath itself was burnt to the ground in the last throws of the war by the shattered remnants of the last Dragonborn army. They slaughtered every Tiefling they could find, but many escaped or were simply not present.