Would the Trans-Atlantic slave trade have gone on as long as it did if a kingdom like Wakanda (from the Marvel Cinematic Universe) had existed at the time?
Wakanda is supposed to be in east Africa south of Ethiopia. The trans-Atlantic slave trade drew on the internecine warfare of west Africa. Wakanda would have had to expand to cover pretty much all of sub-saharan Africa to make a difference to it. Given its technological advantages that’s not unbelievable, but it’s open to question whether they would see much advantage to expanding that far in that direction.