Dungeon World: Leviathan
The Blasted Desert
The Blasted Desert is filled with either sand or cracked red rocks. It stretches on beyond where people can see and nothing humanoid lives there.
Occasionally, not often, but occasionally, things try to make their way over Wall. They are horrible, unholy and unknowable creatures. The wall may stop them, as might the few guards who keep watch while their sanity holds.