> most of the great African empires had collapsed under the onslaught of the slave trade Powerful African states like the Ashanti empire, Dahomey and Kanem Bor

> most of the great African empires had collapsed under the onslaught of the slave trade Powerful African states like the Ashanti empire, Dahomey and Kanem Bornu empire grew and based much of their economy on the wealth of the slave trade, benefiting at the expense of their weaker neighbors whom they "exported", and collapsed only after the slave trade was over, in part because of the loss of that trade revenue. In general, the conquest and colonization (beyond trade posts) of sub-Saharan Africa does not overlap at all with the years of trans-Atlantic slave trade, the collapse of pretty much all the African empires and kingdoms came starting from 1880 after the slave trade had ended. And of course there are earlier great African empires like Mali and Songhai and Kush, but again their collapse had nothing to do with "the onslaught of the slave trade". Arguably the causality is the other way around - the peoples whose empires collapsed due to attacks by neighbours or internal fighting became the victims of the slave trade afterwards, benefiting the economy of their victorious neighboring African empires/kingdoms who then kept raiding the less unified areas for slaves.