Rome and in Africa, long a source of slaves for Europe, though not the only one.
In the Roman period slaves came from Slavic peoples around the Black Sea, from the Middle East, and also from Northern Europe. But by 1400, Europeans had stopped enslaving each other. Africa, however, as we saw in chapter 6, did not undergo the transition from slavery to serfdom as did medieval Europe. Before the early modern period, there was a vibrant slave trade in East Africa, and large numbers of slaves were transported across the Sahara to the Arabian Peninsula. Moreover, the large medieval West African states of Mali, Ghana, and Songhai made heavy use of slaves in the government, the army, and agriculture, adopting organizational models from the Muslim North African states with whom they traded.
It was the development of the sugar plantation colonies of the Caribbean beginning in the early seventeenth century that led to a dramatic escalation of the international slave trade and to an unprecedented increase in the importance of slavery within Africa itself. In the sixteenth century, probably about 300,000 slaves were traded in the Atlantic. They came mostly from Central Africa, with heavy involvement of Kongo and the Portuguese based farther south in Luanda, now the capital of Angola. During this time, the trans-Saharan slave trade was still larger, with probably about 550,000 Africans moving north as slaves. In the seventeenth century, the situation reversed. About 1,350,000 Africans were sold as slaves in the Atlantic trade, the majority now being shipped to the Americas. The numbers involved in the Saharan trade were relatively unchanged. The eighteenth century saw another dramatic increase, with about 6,000,000 slaves being shipped across the Atlantic and maybe 700,000 across the Sahara. Adding the figures up over periods and parts of Africa, well over 10,000,000 Africans were shipped out of the continent as slaves.
Map 15( this page) gives some sense of the scale of the slave trade. Using modern country boundaries, it depicts estimates of the cumulative extent of slavery between 1400 and 1900 as a percent of population in 1400. Darker colors show more intense slavery. For example, in Angola, Benin, Ghana, and Togo, total cumulative slave exports amounted