This article discusses systems, history, and effects of slavery within Africa. See Arab slave trade, Atlantic slave trade, Maafa, and Slavery in contemporary Africa for other discussions. Slavery in Africa has not only existed throughout the continent for many centuries, but continues in the current day. Systems of servitude and slavery were common in parts of the continent, as they were in much of the ancient world. In most African societies where slavery was prevalent, the enslaved people were not treated as chattel slaves and were given certain rights in a system similar to indentured servitude elsewhere in the world. When the Arab slave trade and Atlantic slave trade began, many of the local slave systems changed and began supplying captives for slave markets outside of Africa. Slavery in historical Africa was practiced in many different forms and some of these do not clearly fit the definitions of slavery elsewhere in the world. Debt slavery, enslavement of war captives, military slavery, and criminal slavery were all practiced in various parts of Africa. Although there had been some trade from the interior of Sub-Saharan Africa to other regions, slavery was a small part of the economic life of many societies in Africa until the introduction of transcontinental slave trades (Arab and Atlantic). Slave practices were again transformed with European colonization of Africa and the formal abolition of slavery, which began in the early 19th century.