This was done on slave colonies too. Get a bunch of people from all over west Africa so they all speak different languages. It’s much more difficult to unite people if they can’t communicate. It also helps if there’s some deep seeded hate there too.

Imagine if you had a German and a Russian, or a Turk and a Greek on the same plantation and that’s what you get. They can’t conspire, and they won’t want to conspire because of beef they had in the old country.