Challenge: Have the Africans be the ones running the Atlantic Slave Trade (and the white people be the slaves)

In the TV movie Cracka, the African Americans are in charge and it's the white people who are enslaved.

My challenge is inspired by that TV film's premise. What would need to change regarding the course of events in the TV movie that would lead to the premise of the alternate history TV movie happening?

No, this is not saying I'm pro-slavery. This is merely asking, "What would need to happen to make the premise of an alternate history TV movie possible?"