It is easy to picture the slave trade as something done to Africa by outsiders alone. The reality was more complicated and, in some ways, more disturbing. The trade ran through African states, merchants and markets as well as European ships, and it reshaped the societies that took part in it and the ones that suffered from it.

A continent of states

West and West Central Africa in 1500 held kingdoms, city-states and stateless farming societies, linked by long-distance trade in gold, salt, cloth and kola nuts. Strong rulers controlled who could trade and on what terms. Europeans were in no position to conquer them. Tropical diseases such as malaria and yellow fever killed newcomers at terrible rates, and African armies were formidable. For most of the trade, Europeans operated from coastal forts and trading posts, such as Elmina, built by the Portuguese on the Gold Coast in 1482 and taken by the Dutch in 1637, and they paid local rulers rent and fees for the privilege.

How people were enslaved

Captives were made in several ways. Some were convicted of crimes or witchcraft and sentenced to sale; some were pawned for debts that were never repaid; some were simply kidnapped on a road or at a well. But most captives were first enslaved through wars and raids between African states. Slavery already existed in many African societies, usually as a way of adding dependents to a household or lineage, and prisoners of war had long been enslaved. The Atlantic demand turned that older practice into a vast export business. As prices rose in the eighteenth century, some states fought wars partly to take captives, and raiding spread far inland.

Most people sold to the Atlantic were young adults, roughly two men for every woman, since planters paid more for men and African societies often kept women and children. Children made up a growing share over time.

What Africans received

African sellers drove hard bargains and demanded specific goods. The largest single category of goods exchanged for captives was cloth, much of it from India. Others included iron and copper bars, guns and gunpowder, alcohol, tobacco, and cowrie shells from the Maldive Islands, which served as money around the Bight of Benin. Some historians have described a gun and slave cycle, in which states bought guns to capture people and sold people to buy guns. Others reply that most guns were of poor quality and that wars had many causes. The debate is unsettled.

African responses

African rulers did not all welcome the trade. In 1526 King Afonso I of Kongo, a Christian convert, wrote to the king of Portugal complaining that Portuguese traders were seizing his own subjects, even relatives of his nobles, and asked for limits on the trade. He did not oppose all slavery, but he wanted to control it. In the seventeenth century the Portuguese built a colony at Luanda in Angola and waged long wars inland. Njinga, queen of Ndongo and Matamba, fought Portuguese expansion in Angola for decades, using diplomacy, war and alliances with the Dutch; she also sold captives herself, a reminder that resistance and participation could go together.

Farther north, the kingdom of Dahomey conquered the port of Ouidah in 1727 and made the trade a royal enterprise. The Oyo empire, with its cavalry, and the Asante kingdom on the Gold Coast also grew powerful during the era. Other communities moved to hilltops, marshes or fortified villages to escape raiders.

Regions and lasting effects

Captives came from a long coastline, from Senegambia in the north to Angola in the south, with a smaller flow from Mozambique in the east. West Central Africa, including Kongo and Angola, supplied the largest share of captives, about 45 percent of the total. The Bight of Benin, the Bight of Biafra and the Gold Coast followed.

What did the trade do to Africa? Walter Rodney, a historian from Guyana, argued in 1972 that it drained the continent of people and set back its development. Others stress that some African states grew richer and stronger. Recent research has tried to measure the damage. The economists Nathan Nunn and Leonard Wantchekon found that people from ethnic groups hit hardest by the slave trades show lower trust in others today, a sign of the deep suspicion that generations of kidnapping and betrayal left behind.

Worked example: a captain at Ouidah

Picture a French captain arriving at Ouidah around 1750. He cannot simply land and buy people. First he pays customs duties to Dahomey's officials and gifts to the royal official who oversees European traders. He must wait for the king's own captives to be sold first, and at the king's prices. His cargo is a careful mix: Indian cloth, cowrie shells, brandy and guns, chosen because his agents know what Dahomey's merchants want this season. Buying a full cargo may take months, while the captives already bought wait in a crowded fort and some fall sick.

Now consider the people he buys. Many were captured in Dahomey's wars against neighbors, marched to the coast, and held in pens. They speak different languages and may come from enemy peoples. The scene shows real African power: rulers set terms, collected revenue and kept Europeans on the coast. It also shows that this power fed on the misery of other Africans, and that the wealth flowing to a few rulers came at the cost of whole regions emptied by raids.