The Black City is an ancient ruin in Tortall's Great Southern Desert which dates back at least to the Old Ones. The Bazhir cursed the city in order to cage the Ysandir, demons who ruled the Black City in ages past. The Ysandir steal the souls and drain they magic of those who enter their city. The Bazhir's caged them inside the city by placing a ring of fire around it. The Bazhir built Persepolis in order to keep an eye on the Black City.
Bazhir youth were sometimes compelled by magic to escape and ride to the Black City, where the Ysandir would consume them. In 433 HE[1], Alanna of Trebond and Jonathan of Conté, then a page and squire, respectively, visited the city and vanquished the Ysandir with the help of the Great Gods.