Bornu Empire
Since the populations were partially affiliated with the Arab Muslim culture of North Africa, they started to trade and be referred to by the Arabic speakers as "Al-Sudan" (meaning "The Blacks") as they were considered an extended part of the Muslim world. There are early historical references by medieval Arab and Muslim historians and geographers which to refer to the Kanem-Bornu Empire as the region's major centre for Islamic civilization. It is likely that the medieval Hausa Kingdoms formed trading ties with the Bornu Empire, which became increasingly wealthy as the main African transshipment centre for the trans-Saharan slave trade. Hausa rulers also likely provided Sudanic peoples as a tributary to the Bornu Empire in order to avert war with the Empire.