A Short History of the African Slave Trade

Illustration depicting slave traffic on the coast of Africa
Chicago History Museum / Getty Images

Although slavery has been practiced for almost the whole of recorded history, the vast numbers involved in the African slave trade has left a legacy which cannot be ignored.

Slavery in Africa

Whether slavery existed within sub-Saharan African Iron Age kingdoms before the arrival of Europeans is hotly contested among African studies scholars. What is certain is that Africans were subjected to several forms of slavery over the centuries, including chattel slavery under both the imperial Muslims with the trans-Saharan slave trade and imperial Christian Europeans through the trans-Atlantic slave trade.

Between 1400 and 1900, close to 20 million individuals were taken from the African continent during four sizable and mostly simultaneous slave trading operations: Trans-Saharan, Red Sea (Arab), Indian Ocean, and Trans-Atlantic. According to Canadian economic historian Nathan Nunn, by 1800 Africa’s population was half of what it would have been, had the slave trades not occurred. Nunn suggests his estimates based on shipping and census data probably represent about 80% of the total number of people stolen from their homes by the various slave operations.

Four Great Slave Trading Operations in Africa
Name Dates Number Countries Most Impacted Destination
Trans-Saharan early 7th–1960s >3 million 13 countries: Ethiopia, Mali, Nigeria, Sudan, Chad North Africa
Trans-Atlantic 1500–1850 >12 million 34 countries: Angola, Ghana, Nigeria, the Congo European colonies in the Americas
Indian Ocean 1650–1700 >1 million 15 countries: Tanzania, Mozambique, Madagascar Middle East, India, Indian Ocean Islands
Red Sea 1820–1880 >1.5 million 7 countries: Ethiopia, Sudan, Chad Egypt and Arabian peninsula

Religion and African Slavery

Many of the countries who actively enslaved Africans came from states with strong religious underpinnings such as Islam and Christianity. The Qur'an prescribes the following approach to slavery: free men could not be enslaved, and those faithful to foreign religions could live as protected persons. However, the spread of the Islamic Empire through Africa resulted in a much harsher interpretation of the law, and people from outside the borders of the Islamic Empire were considered an acceptable source of slaves.

Before the Civil War, Christianity was used to justify the institution of slavery in the American south, with most clergy in the south believing and preaching that slavery was a progressive institution designed by God to affect the Christianization of Africans. The use of religious justifications for slavery is not confined to Africa by any means.

The Dutch East India Company

Africa wasn't the only continent from which slaves were captured: but its countries suffered the most devastation. In many cases, slavery appears to have been a direct outgrowth of expansionism. The great maritime explorations driven by companies such as the Dutch East India Company (VOC) were financed for the specific purpose of adding land to European empires. That land required a labor force far beyond the men sent on exploratory ships. People were enslaved by empires to act as servants; as agricultural, mining, and infrastructure labor; as sex slaves; and as cannon fodder for various armies.

The Start of the Trans-Atlantic Slave Trade

When the Portuguese first sailed down the Atlantic African coast in the 1430s, they were interested in one thing: gold. However, by 1500 they had already traded 81,000 Africans to Europe, nearby Atlantic islands, and to Muslim merchants in Africa.

São Tomé is considered to be a principal port in the export of slaves across the Atlantic, this is, however, only part of the story.

The 'Triangular Trade' in Slaves

For two hundred years, 1440–1640, Portugal had a monopoly on the export of slaves from Africa. It is notable that they were also the last European country to abolish the institution—although, like France, it still continued to work former slaves as contract laborers, which they called libertos or engagés à temps. It is estimated that during the 4 1/2 centuries of the trans-Atlantic slave trade, Portugal was responsible for transporting over 4.5 million Africans (roughly 40% of the total). During the eighteenth century, however, when the slave trade accounted for the transport of a staggering 6 million Africans, Britain was the worst transgressor—responsible for almost 2.5 million. (This is a fact that is often forgotten by those who regularly cite Britain's prime role in the abolition of the slave trade.)

Information on how many slaves were shipped from Africa across the Atlantic to the Americas during the sixteenth century can only be estimated as very few records exist for this period. But from the seventeenth century onwards, increasingly accurate records, such as ship manifests, are available.

Slaves for the Trans-Atlantic slave trade were initially sourced in Senegambia and the Windward Coast. Around 1650 the trade moved to west-central Africa (the Kingdom of the Kongo and neighboring Angola).

South Africa

It is a popular misconception that slavery in South Africa was mild compared to that in America and the European colonies in the Far East. This is not so, and punishments meted out could be very harsh. From 1680 to 1795 an average of one slave was executed in Cape Town each month and the decaying corpses would be re-hung around town to act as a deterrent to other slaves. 

Even after the abolition of the slave trade in Africa, colonial powers used forced labor—such as in King Leopold's Congo Free State (which was operated as a massive labor camp) or as libertos on the Portuguese plantations of Cape Verde or São Tomé. As recently as the 1910s, about half of the two million Africans who supported the various powers in World War I were forcibly coerced to do so.

Impact of the Slave Trade

Historian Nathan Nunn has conducted extensive research on the economic impacts of the massive loss of population during the slave trade. Prior to 1400, there were several Iron Age kingdoms in Africa that were established and growing. As the slave trade ramped up, people in those communities needed to protect themselves and began procuring weapons (iron knives, swords, and firearms) from Europeans by trading slaves.

People were kidnapped first from other villages and then from their own communities. In many regions, the internal conflict caused by that led to the disintegration of kingdoms and their replacement by warlords who could not or would not establish stable states. The impacts continue to this day, and despite great indigenous strides in resistance and economic innovation, Nunn believes the scars still hinder the economic growth of countries who lost large numbers of populations to the slave trade compared to those which did not. 

Selected Sources and Further Reading