Africa was raided/colonised. For example, historically Ukraine and Russia were constantly raided by Vikings, Mongols and Ottoman Turks with 100K enslaved at a time in some cases. I'd say this was being carried out over almost half a millennium. Not to forget, Romans and Greeks being the other fine examples of this European enterprising spirit.

Not that I disagree that Europeans (mainly British and Portuguese) in Africa were not especially enterprising using modern financial instruments, and carrying it out on industrial scale, so to speak.

Some of the brutality of European slavers in Africa was especially shocking, Belgians probably being the worst:

https://en.wikipedia.org/wiki/King_Leopold%27s_Ghost

In America this lingered on after British abolished slavery in mid 19th cent. Just reading Kimberley's "Prejudential" about US founding fathers/slavers and so on.