Forgive me if I'm misunderstanding the question - I suspect you may be referring to The Scramble for Africa and such things. If that is not the case though, Inhuman Bondage: the Rise and Fall of Slavery in the New World by David Brion Davis may be what you're looking for. He has studied the slavery as a part of the initial colonization of the Americas up until the Civil War. It is a fascinating book because it focuses on an aspect of the triangular trade that's usually only mentioned in passing, like you describe yourself.