Kilwa Kisiwani is a community on an island off the southern coast of present-day Tanzania in eastern Africa. Historically, it was the center of the Kilwa Sultanate, a medieval sultanate whose authority at its height in the 13th-15th centuries AD stretched the entire length of the Swahili Coast. Kilwa Kisiwani has been designated a UNESCO World Heritage Site along with the nearby stonetown Songo Mnara.