Answer:
Involved the enslavement of criminals, debtors, and war captives.
Step-by-step explanation:
Slavery already existed in humanity long before Europeans made money out of it. In Africa specifically, it existed for centuries. Africans did not sell to buy slaves for money, neither their economy depends on it. Also, Africans did not make slavery a matter of the racial or ethnic group.
Africans used to enslave war captives, criminals, debtors, and social misfits. Also, it was very common for families to give children up to pay a debt or as a part of a bridal dowry.
Important to know that slaves at that time were not considered property like slaves were considered in the American colonies, they had better treatment and had some rights such as marry, own property and had control over their lives.