Rilutaan: The Western Marches
One of the Lower Planes, Gehanna is a miserable plane, featuring bleak, wind-swept plains and jagged, craggy mountains that plunge down to fetid, hot ravines and boggy marshes, all between layers of volcanoes that create distinct layers that float in space. The top-most layer is hot and full of lava flows. The bottom layer is an icy, dead place. The fiends known as the Yugoloths hail from this plane of existence, calling it home. There are other famous denizens of the plane, including a trio of hags known as the Night Sisters and a fearsome fiend known only as the General of Gehanna, the leader of the yugoloths, who commands the Crawling City.
Some monstrous gods supposedly call Gehanna home, having different realms on the plane.