Both Muslims and Christians engaged in the slave trade in the Middle Ages, with the only general prohibition being enslavement or trading of co-religionists. The Muslim kingdoms of North Africa dominated trans-Saharan trade was dominated, using as their intermediaries the various African empires that grew to occupy the western and central Sahara and its southern borders. The earliest, and most enduring, of these empires were Ghana, to the west, and Kanem to the east. From the 13th century, first the Malian, then the Songhay empires supplanted that of Ghana; while Kanem was succeeded by Bornu. The slaves initially were drawn from vanquished peoples in wars of conquest; as these sub-Saharan kingdoms progressively became Islamized, the slaves would increasingly be sourced from unconverted tribes in tropical West Africa and the Great Lakes region of East Africa. Main routes ran from Awdaghust to Sjilimasssa; Timbuktu to Tunis, and Gao to Egypt.
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