The revolt of African slaves in Iraq from 869 to 883 C.E.* - the revolt of the Zanj - was one of the great rebellions of world history and the first major uprising in the history of the African diaspora. The Zanj were black slaves shipped overseas from East Africa to work in salt mines and plantations under the harshest conditions. Their fate resembled that of black slaves in the trans-Atlantic slave trade, and their revolt triggered racism against blacks among Arabs. Like the Spartacus revolt, it threatened a world power, in this case the Abbasid empire. The revolt also inspired solidarity among Africans in the diaspora, when black soldiers of the Caliph deserted and joined the revolt.

Popovic's book is the only full-length study in any major language on the revolt of the Zanj. Scholars on slavery, the African diaspora, and Middle Eastern studies have lauded and extensively quoted from Popovic's groundbreaking work.

*The title refers to the two calendars commonly used to document history in Islamic nations - the Gregorian calendar as well as the Muslim Hijra calendar, which began in 622 C.E. during the migration of Muhammad and his followers to Medina (the Hijra). Thus the revolts from 869 to 883 C.E. took place in the third Hijra century but the ninth Gregorian century.