They have a really blinkered view of history, don't they lol. Even the noble brown skins conquered other people and took slaves. White slaves, in several instances. Even the noble Muslims took slaves from Europe. The men were either castrated or worked to death while the women were made into sex slaves. Here in the US, The Navaho fought the Iroquois and the Apache fought them both.
The white folks of the time were doing pretty much what everyone else at the time was doing. They're biggest sin was/is they were more efficient at it than most. But contemporary liberals sit in the comfort of their computer chairs and morally condemn people for doing what, they themselves no doubt, would have done under the same historical circumstances.
And if they can't prove otherwise, we'll all understand, lol.