This article discusses the history of the slave trade of Africa, and its effect upon the continent.

Slavery within Africa, as with every other continent, has a long history with internal slavery being common to many societies. However, due to lack of historical records we can only discuss the early history of the African slave trade through its external manifestation, whereby slaves were supplied slaves across the Sahara Desert and the Red Sea.

The earliest external slave trade was that across the Sahara Desert. While there has long been some trading up the Nile River and very limited trading across the western dessert the transportation of large numbers of slaves did not become viable until camels were introduced from Arabia in the tenth century. At this point a trans-Saharan trading network, of which slaves were exported north. There is little hard evidence of numbers, but it has been estimated that some 6000 of 7000 slaves were transported north each year. While over time this added up to several million people moving north, the annual numbers were small enough that it had little demographic effect on either West Africa or the Maghreb. Frequent intermarriages meant that the black slaves were quickly assimilated. Unlike in the Americas, slaves in North Africa were mainly servants rather than labourers, and an equal or greater number of females than males were taken, who often became concubines to their owners. It was also not uncommon to turn male slaves into eunuchs.

The trade in slaves over the Indian Ocean also has a long history beginning with the control of the sea routes by Arab traders in the ninth century. It is estimated that only a few thousand slaves were taken each year from the Red Sea and Indian Ocean coast. They were sold throughout the Middle East and India. This trade accelerated as superior ships lead to more trade and greater demand for labour on plantations in the region. Eventually tens of thousands per year were being taken.

The Atlantic slave trade developed far later, but it would eventually be by far the largest and have the greatest impact. The first Europeans to arrive on the coast of Guinea were the Portuguese. Originally interested in trading mainly for gold and spices they set up colonies on the uninhabited islands of Sao Tome. In the sixteenth century the Portuguese settlers found that the volcanic islands were ideal for growing sugar. Sugar growing is a labourious project and Portuguese settlers were very hard to attract. To cultivate the sugar the Portuguese thus turned to large numbers of African slaves.

Increasing penetration of the Americas by the Portuguese created another huge demand for labour in Brazil, for farming, mining, and other tasks. To meet this a trans-Atlantic slave trade soon developed. The slave economies quickly spread to the Caribbean and the southern portion of what is today the United States. These areas all developed an insatiable demand for slaves. From its beginning it is estimated that some twelve million slaves left Africa for the Americas, of which 10.5 million arrived alive. The result of this trade is one of the largest migrations in history. These numbers are hotly disputed by scholars, and precision is quite difficult. Today, general consensus is that the totals are somewhat near these number. A small number of slaves were also shipped to Europe while some were also transported to other areas of Africa, mostly to South Africa.

While no one disputes the horrific harm done to the slaves themselves, the effects on African societies are much debated. While the numbers of slaves exported were large, so was the population they were drawn from. At its peak the Atlantic slave trade took almost 90,000 slaves per year out of a total population of around twenty-five million in Guinea, where the vast majority originated. This number was significant, but only a moderate annual growth rate in population was enough to sustain it. The slave trade is unlikely to have caused a decrease in the population of West Africa, but it did quite likely greatly reduce or even halt population growth in the region.

All three slave trades tapped into local trading pattern, while there were occasional expeditions by Europeans or Arabs in Africa to capture slaves these were rare. It was far easier to make use of African middlemen. Slavery had long been present in Africa, though some historians prefer to describe African slavery as feudalism, arguing it was more like the system that controlled the peasantry of Western Europe during the Middle Ages or Russia into the 19th century than slavery as it was practiced in the Americas.

The slaves came from many different sources. About half came from the society that sold them. These were criminals, heretics, the mentally ill, the indebted, and any others that fell out of favour with the rulers. Little is known about practices before the arrival of Europeans and so it is difficult to tell if the number of people considered undesirables was artificially increased in order to provide more possible slaves for export. It is believed that capital punishment and human sacrifice in the region almost disappeared as prisoners became far too valuable to dispose of in such a manner.

The other source of slaves, adding up to about half the total, came from military conquests of other states or tribes. It has long been contended that the slave trade greatly increased violence and warfare in the region due to the pursuit of slaves, but it is very hard to find any evidence to prove this.

Slaves were an expensive commodity, and the traders and rulers of the African states received a great deal in exchange for condemning a significant some of their population into slavery. At the peak of the slave trade hundreds of thousands of muskets, vast quantities of cloth, gunpowder, and metals, were being shipped to Guinea. Guinea's trade with Europe at the peak of the slave trade, which also included significant exports of gold and ivory was some 3.5 million pounds per year. By contrast the trade of the United Kingdom, the economic superpower, was about 14 million pounds per year over this same period of the late 18th century. Thus for those left behind in Africa the standard of living increased substantially and the region became divided into highly centralized and powerful nation states, such as Dahomey and the Ashanti Confederacy. It also created a class of very wealthy, and highly Europeanized, traders who began to send their children to European universities.

Beginning in he late eighteenth century reaction against the barbarities of the slave trade lead to it being outlawed first in the United Kingdom and then in the rest of Europe. The power of the Royal Navy was subsequently used to suppress the slave trade, and while some illegal trade, mostly with Brazil, continued, the Atlantic slave trade was eradicated by early in the nineteenth century. The Saharan and Indian Ocean trades continued, and even increased as new supplies of slaves became available. The salve trade within Africa also increased. The British Navy could suppress much of the trade in the Indian Ocean, but the European powers could do little to affect to transcontinental trade.

The continuing anti-slavery movement in Europe, fueled by reports from such figures as David Livingstone became an important motivator, and excuse, for the European penetration and conquest of the African continent. The Scramble for Africa saw the continent rapidly divided between Europeans in the late nineteenth century, and an early focus of all colonial regimes was the suppression of slavery and the slave trade.

By the end of the colonial period they were largely successful in this aim, and slavery had largely been abolished as Africa was moved to a wage economy. Slavery has never been completely eradicated, and it sometimes reappears in states where law and order have collapsed, such as in Sudan.

See also

• Slavery
• Atlantic slave trade
• Slavery in the Americas
• History of slavery in the United States