The African slave trade refers to the historic slave trade within Africa. Systems of servitude and slavery were common in many parts of the continent, as they were in much of the ancient world. In some African societies, the enslaved people were also indentured servants and fully integrated; in others, they were treated much worse. When the Arab slave trade and Atlantic slave trade began, many local slave systems changed and began supplying captives for slave markets outside of Africa.

In certain African societies, there was very little difference between the free peasants and the feudal vassal peasants. Enslaved people of the Songhay Empire were used primarily in agriculture; they paid tribute to their masters in crop and service but they were slightly restricted in custom and convenience. These non-free people were more an occupational caste, as their bondage was relative.

Several nations such as the Ashanti of Ghana and the Yoruba of Nigeria were involved in slave-trading. Groups such as the Imbangala of Angola and the Nyamwezi of Tanzania would serve as intermediaries or roving bands, waging war on African states to capture people for export as slaves. Historians John Thornton and Linda Heywood of Boston University estimate that 90 percent of those shipped to the New World were enslaved by Africans and then sold to European traders. Without the complex business partnerships between African elites and European traders and commercial agents, the slave trade to the New World would have been impossible, at least on the scale it occurred.

The history of slavery covers slave systems in historical perspective in which one human being is legally the property of another, can be bought or sold, is not allowed to escape and must work for the owner without any choice involved. As Drescher (2009) argues, "The most crucial and frequently utilized aspect of the condition is a communally recognized right by some individuals to possess, buy, sell, discipline, transport, liberate, or otherwise dispose of the bodies and behavior of other individuals." An integral element is that children of a slave mother automatically become slaves. It does not include historical forced labor by prisoners, labor camps, or other forms of unfree labor in which laborers are not considered property.

Slavery can be traced back to the earliest records, such as the Code of Hammurabi (c. 1760 BC), which refers to it as an established institution. Slavery is rare among hunter-gatherer populations as slavery depends on a system of social stratification. Slavery typically also requires a shortage of labor and a surplus of land to be viable.

William Wilberforce (24 August 1759 – 29 July 1833) was a British politician, philanthropist, and a leader of the movement to abolish the slave trade. A native of Kingston upon Hull, Yorkshire, he began his political career in 1780, eventually becoming the independent Member of Parliament for Yorkshire (1784–1812). In 1785, he underwent a conversion experience and became an evangelical Christian, resulting in major changes to his lifestyle and a lifelong concern for reform. In 1787, he came into contact with Thomas Clarkson and a group of anti-slave-trade activists, including Granville Sharp, Hannah More and Charles Middleton. They persuaded Wilberforce to take on the cause of abolition, and he soon became one of the leading English abolitionists. He headed the parliamentary campaign against the British slave trade for twenty-six years until the passage of the Slave Trade Act of 1807.

Wilberforce was convinced of the importance of religion, morality and education. He championed causes and campaigns such as the Society for Suppression of Vice, British missionary work in India, the creation of a free colony in Sierra Leone, the foundation of the Church Mission Society, and the Society for the Prevention of Cruelty to Animals. His underlying conservatism led him to support politically and socially repressive legislation, and resulted in criticism that he was ignoring injustices at home while campaigning for the enslaved abroad.

Bartolomé de las Casas O.P. (c. 1484 – 18 July 1566) was a 16th-century Spanish historian, social reformer and Dominican friar. He became the first resident Bishop of Chiapas, and the first officially appointed "Protector of the Indians." His extensive writings, the most famous A Short Account of the Destruction of the Indies and Historia de Las Indias, chronicle the first decades of colonization of the West Indies and focus particularly on the atrocities committed by the colonizers against the Indigenous peoples.