Athas
For thousands of years, the Tablelands have remained untouched: its politics frozen in a frail stalemate, its life in a delicate balance.
It is true that the Dragon Kings amuse themselves with their petty wars, rattling sabers to punctuate the passing of ages. It is true that, occasionally, another city would be swallowed by the wastes. But there are few surprises. The Dragon Kings steer everything from their omnipotent perches, content in their superiority, but ever thirsting for challenge.
All that is about to change. The Tablelands are about to be thrown into turmoil, the likes of which have not been seen since times forgotten. The worst is yet to come. Change is in the air, and change has never come gently to Athas.
(This 5e D&D campaign will be run loosely off of the official Dark Sun setting, with plenty of home-rules and deviation from the original lore.)