There is a Russian Sci-Fi novella

called "Missionaries".

It's about a group of people who found a rip in reality and traveled back in time to some Polynesian islands where they decided to help the locals against an inevitable arrival of the European colonizers.
And there were two tribes locked in a conflict on these islands but when the future-people tried to warn them they weren't impressed. "What you are talking about? We are great warriors. Our boats are fast, our wooden spears are sharp and our stone maces are fearsome. We are afraid of no one".
So they used a different approach - a little provocation. They attacked the both sides using simple delta-wing flyers and homemade grenades. "Well, if our opponents abandoned all honor and went to the outsiders for help, thought the both tribes, then we will too".
Fast-forward 60 years. The conflict is now spanning many islands. They have guns and some kind of napalm, planes and turbine ships. They use sugar-cane alcohol for fuel.
And this is when the Europeans arrive. In their slow wooden ships with sails, with their muzzle-loading guns, armor and swords. And they, or so the islanders were told, come from a large continent filled with various resources and there is also this thing called oil?
They sink all ships but one letting the last one lead them to Europe...


And that's what would have happened if Wakanda really existed. The vibranium clad warriors would have rolled over Egypt, Persia, Greece and Rome with the elite mutant panther-soldier ripping the whole units to shreds. A then they would spread out all over Eurasia, eventually colonizing both Americas and Australia. It's possible the fate of other black people would have been better in that world but I doubt it.
Inevitably the elite of herb-eaters would emerge and at some point there would be an internal strife, dynastic disputes etc with mutant superwarriors leading mobs of white, yellow, red, brown or black barbarians to slaughter. And so on and so forth...

Because this is how humans are and if there is one thing the movie proves it's that, despite all the vibranium radiation, the Wakandas are very much human.