Sackcloth & Ashes
Sheol appears to be some sort of purgatory that has grown without boundaries. It attracts lost souls from many planes, although groups with shared backgrounds seem to be more likely to appear together. Newcomers always appear during a New Moon, at least in the city of Tanakh.
While other cities are known to exist, they are rarely visited due to the dangers of travel. There are armored caravans that travel between the cities roughly once every year or two. The Caravan Guild jealously guards the information about the world at large as their information gives them a virtual monopoly on trade and travel between the cities. The only city that even comes close to rivaling Tanakh in size is its’ far flung sister city of Barzakh which features a bottomless abyss named Tartarus, a feature believed by the world’s foremost scholars to be a sort of inversion of Tanakh’s Great Tower, The Etemenanki.