Phoenician, Greek, and Roman came into touch more or less with black Africa. Carthage, that North African city of a million men, had a large caravan trade with Negroland in ivory, metals, cloth, precious stones, and slaves. Black men served in the Carthaginian armies and marched with Hannibal on Rome. In some of the North African kingdoms the infiltration of Negro blood was very large and kings like Massinissa and Jugurtha were Negroid. By way of the Atlantic the Carthaginians reached the African west coast. Greek and Roman influences came through the desert, and the Byzantine Empire and Persia came into communication with Negroland by way of the valley of the Nile. The influence of these trade routes, added to those of Egypt, Ethiopia, Benin, and Yoruba, stimulated centers of culture in the central and western Sudan, and European and African trade early reached large volume.
Negro soldiers were used largely in the armies that enabled the Mohammedans to conquer North Africa and Spain. Beginning in the tenth century and slowly creeping across the desert into Negroland, the new religion found an already existent culture and came, not a conqueror, but as an adapter and inspirer. Civilization received new impetus and a wave of Mohammedanism swept eastward, erecting the great kingdoms of Melle, the Songhay, Bornu, and the Hausa states. The older Negro culture was not overthrown, but, like a great wedge, pushed upward and inward from Yoruba, and gave stubborn battle to the newer culture for seven or eight centuries.
Then it was, in the fifteenth century, that the heart disease of Africa developed in its most virulent form. There is a modern theory that black men are and always have been naturally slaves. Nothing is further from the truth. In the ancient world Africa was no more a slave hunting ground than Europe or Asia, and both Greece and Rome had much larger numbers of white slaves than of black. It was natural that a stream of black slaves should have poured into Egypt, because the chief line of Egyptian conquest and defense lay toward the heart of Africa. Moreover, the Egyptians, themselves of Negro descent, had not only Negro slaves but Negroes among their highest nobility and even among their Pharaohs. Mohammedan conquerors enslaved peoples of all colors in Europe, Asia, and Africa, but eventually their empire centered in Asia and Africa and their slaves came principally from these countries. Asia submitted to Islam except in the Far East, which was self-protecting. Negro Africa submitted only partially, and the remaining heathen were in small states which could not effectively protect themselves against the Mohammedan slave trade. In this wise the slave trade gradually began to center in Africa, for religious and political rather than for racial reasons.