airwalkrr's Out of the Abyss
The disaster in question, in 5094 SD (or -422 CY), was precipitated when the Suloise Mages of Power, who practiced a kind of magic unknown to the present day, created a terrible cataclysm remembered as the Invoked Devastation. The details of this calamity are unclear, except the fertile heartlands of the Baklunish empire were transformed into the Dry Steppes, her great cities and rivers now entirely gone. There are not even ruins to mark the graves of ancient Baklunish civilization; Tovag Baragu stands alone where there was once a capital city.
The kingdoms of the dwarves in the northern Crystalmists and Sulhauts were also devastated, the legendary Axe of the Dwarvish Lords lost.
In retribution, the magi-priests of the Bakluni gathered within the stone circles of Tovag Baragu and conjured a mighty working, bringing down the terrible Rain of Colorless Fire upon the Suloise basin. This Rain burned people, buildings, even rocks and soil to ash, leaving the Sea of Dust as a monument to the hubris of Man. Together, the Invoked Devastation and the Rain of Colorless Fire are known as the Twin Cataclysms.
Thus ended the Baklunish-Suloise Wars.