Classical slavery was practiced for a time in Europe as well, and chattel slavery was not exclusive to European diaspora; It was also practiced by Imperial Japan on Koreans and Chinese, for instance.

You usually see this sort of comment when people are trying to dismiss the harm done by Europeans during the slave trade. It's usually done to say the Africans were already participating, so the Europeans did nothing wrong and were just willful participants. The Africans were barbarians naturally. They created the system and not the Europeans, who just happened to end up capitalizing on it. This isn't true. It's white suprimist apologism and should be countered whenever it's seen, not indulged.

I don't know if this is what the OP intended, but it shouldn't be allowed to spread without correction regardless.