Our new understanding of the scope of African involvement in the slave trade is not historical guesswork. Thanks to the Trans-Atlantic Slave Trade Database, directed by the historian David Eltis of Emory University, we now know the ports from which more than 450,000 of our African ancestors were shipped out to what is now the United States (the database has records of 12.5 million people shipped to all parts of the New World from 1514 to 1866). About 16 percent of United States slaves came from eastern Nigeria, while 24 percent came from the Congo and Angola.

Through the work of Professors Thornton and Heywood, we also know that the victims of the slave trade were predominantly members of as few as 50 ethnic groups. This data, along with the tracing of blacks’ ancestry through DNA tests, is giving us a fuller understanding of the identities of both the victims and the facilitators of the African slave trade.

For many African-Americans, these facts can be difficult to accept. Excuses run the gamut, from “Africans didn’t know how harsh slavery in America was” and “Slavery in Africa was, by comparison, humane” or, in a bizarre version of “The devil made me do it,” “Africans were driven to this only by the unprecedented profits offered by greedy European countries.”

But the sad truth is that the conquest and capture of Africans and their sale to Europeans was one of the main sources of foreign exchange for several African kingdoms for a very long time. Slaves were the main export of the kingdom of Kongo; the Asante Empire in Ghana exported slaves and used the profits to import gold. Queen Njinga, the brilliant 17th-century monarch of the Mbundu, waged wars of resistance against the Portuguese but also conquered polities as far as 500 miles inland and sold her captives to the Portuguese. When Njinga converted to Christianity, she sold African traditional religious leaders into slavery, claiming they had violated her new Christian precepts.

Did these Africans know how harsh slavery was in the New World? Actually, many elite Africans visited Europe in that era, and they did so on slave ships following the prevailing winds through the New World. For example, when Antonio Manuel, Kongo’s ambassador to the Vatican, went to Europe in 1604, he first stopped in Bahia, Brazil, where he arranged to free a countryman who had been wrongfully enslaved.

African monarchs also sent their children along these same slave routes to be educated in Europe. And there were thousands of former slaves who returned to settle Liberia and Sierra Leone. The Middle Passage, in other words, was sometimes a two-way street. Under these circumstances, it is difficult to claim that Africans were ignorant or innocent.