Xuthltan is the name for two very different things from the Cthulhu Mythos.
Village in modern-day Hungary that was later replaced by Stregoicavar. A cult in Xuthltan was known for its bloody rituals around the Black Stone. In 1526, a Muslim army passed through Xuthltan; disgusted by the cult's horrible rites, they destroyed the settlement and its people.
An Arabian sorceror who, according to legend, stole the gem known as the Fire of Asshurbanipal from a sleeping demon. He was imprisoned by the king of Kara-Shehr after visiting that city. The king tortured Xuthltan to death in his efforts to force him to give him the gem; as he died, Xuthltan laid a horrible curse upon Kara-Shehr and its people.
Some suggest the village's name is a corruption of the word "Cthulhu."
- The Encyclopedia Cthulhiana (Expanded and Revised Second Edition) (2003)