The Zanj Rebellion was a major uprising against the Abbasid Caliphate. It was centered near the city of Basra, located in present-day southern Iraq, and lasted over a period of fourteen years (AD 869–883) before finally being defeated. The insurrection is traditionally believed to have involved enslaved blacks (Zanj) that had originally been captured from the East African coast and transported to the Middle East. It grew to involve many slaves and free men from several regions of the Muslim empire and claimed tens of thousands of lives in lower Iraq. The precise composition of the rebels is debated among historians, both as regards their identity and as to the proportion of slaves and free among them – available historical sources being open to various interpretations.