The Atlantic slave trade and slavery in the Americas represented the most recent large-scale expression of a very widespread human practice — the owning and exchange of human beings. It was present in some early gathering and hunting societies, among some village-based agricultural peoples, and in pastoral communities. But the practice flourished most widely in civilizations where it was generally accepted as a perfectly normal human enterprise and was closely linked to warfare and capture. Before 1500, the Mediterranean and Indian Ocean basins were the major arenas of the Old World slave trade, and southern Russia was a major source of slaves. Many African societies likewise both practiced slavery themselves and sold slaves into these international commercial networks. A trans-Saharan slave trade had long funneled African captives into Mediterranean slavery, and an East African slave trade from at least the seventh century C.E. brought Africans into the Middle East and the Indian Ocean basin. Both operated largely within the Islamic world and initiated the movement of African peoples beyond the continent itself.

Furthermore, slavery came in many forms. Although slaves were everywhere vulnerable “outsiders” to their masters’ societies, in many places they could be integrated into their owners’ households, lineages, or communities. In the Indian Ocean world, for example, African slaves were often assimilated into the societies of their owners and lost the sense of a distinctive identity that was so prominent in North America. In some places, children inherited the slave status of their parents; elsewhere those children were free persons. Within the Islamic world, where most slaves worked in domestic settings, the preference was for female slaves by a two-to-one margin, while the later Atlantic slave trade, which funneled captives into plantation labor, favored males by a similar margin. Not all slaves, however, occupied degraded positions. Some in the Islamic world acquired prominent military or political status. Most slaves in the premodern world worked in their owners’ households, farms, or shops, with smaller numbers laboring in large-scale agricultural or industrial enterprises.

The slavery that emerged in the Americas was distinctive in several ways. One was simply the immense size of the traffic in slaves and its centrality to the economies of colonial America. Furthermore, this New World slavery was largely based on plantation agriculture and treated slaves as a form of dehumanized property, lacking any rights in the society of their owners. Slave status throughout the Americas was inherited across generations, and there was little hope of eventual freedom for the vast majority. Nowhere else, with the possible exception of ancient Greece, was widespread slavery associated with societies that affirmed values of human freedom and equality. Perhaps most distinctive was the racial dimension: Atlantic slavery came to be identified wholly with Africa and with “blackness.” How did this exceptional form of slavery emerge?

The origins of Atlantic slavery clearly lie in the Mediterranean world and with that now-common sweetener known as sugar. Until the Crusades, Europeans knew nothing of sugar and relied on honey and fruits to sweeten their bland diets. However, as they learned from the Arabs about sugarcane and the laborious techniques for producing usable sugar, Europeans established sugar-producing plantations within the Mediterranean and later on various islands off the coast of West Africa. It was a “modern” industry, perhaps the first one, in that it required huge capital investment, substantial technology, an almost factory-like discipline among workers, and a mass market of consumers. The immense difficulty and danger of the work, the limitations attached to serf labor, and the general absence of wageworkers all pointed to slavery as a source of labor for sugar plantations.

Initially, Slavic-speaking peoples from the Black Sea region furnished the bulk of the slaves for Mediterranean plantations, so much so that “Slav” became the basis for the word “slave” in many European languages. In 1453, however, when the Ottoman Turks seized Constantinople, the supply of Slavic slaves was effectively cut off. At the same time, Portuguese mariners were exploring the coast of West Africa; they were looking primarily for gold, but they also found there an alternative source of slaves available for sale. Thus, when sugar, and later tobacco and cotton, plantations took hold in the Americas, Europeans had already established links to a West African source of supply. They also now had religious justification for their actions, for in 1452 the pope formally granted to the kings of Spain and Portugal “full and free permission to invade, search out, capture, and subjugate the Saracens [Muslims] and pagans and any other unbelievers … and to reduce their persons into perpetual slavery.”26 Largely through a process of elimination, Africa became the primary source of slave labor for the plantation economies of the Americas. Slavic peoples were no longer available; Native Americans quickly perished from European diseases; marginal Europeans were Christians and therefore supposedly exempt from slavery; and European indentured servants, who agreed to work for a fixed period in return for transportation, food, and shelter, were expensive and temporary. Africans, on the other hand, were skilled farmers; they had some immunity to both tropical and European diseases; they were not Christians; they were, relatively speaking, close at hand; and they were readily available in substantial numbers through African-operated commercial networks.

Moreover, Africans were black. The precise relationship between slavery and European racism has long been a much-debated subject. Historian David Brion Davis has suggested the controversial view that “racial stereotypes were transmitted, along with black slavery itself, from Muslims to Christians.”27 For many centuries, Muslims had drawn on sub-Saharan Africa as one source of slaves and in the process had developed a form of racism. The fourteenth-century Tunisian scholar Ibn Khaldun wrote that black people were “submissive to slavery, because Negroes have little that is essentially human and have attributes that are quite similar to those of dumb animals.”28

Other scholars find the origins of racism within European culture itself. For the English, argues historian Audrey Smedley, the process of conquering Ireland had generated by the sixteenth century a view of the Irish as “rude, beastly, ignorant, cruel, and unruly infidels,” perceptions that were then transferred to Africans enslaved on English sugar plantations of the West Indies.29 Whether Europeans borrowed such images of Africans from their Muslim neighbors or developed them independently, slavery and racism soon went hand in hand. “Europeans were better able to tolerate their brutal exploitation of Africans,” writes a prominent world historian, “by imagining that these Africans were an inferior race, or better still, not even human.”30