You might enjoy an article I wrote on Medium that tries to cover some pre-colonial African nations:

https://medium.com/restive-souls/to-fix-racism-i-had-to-delete-the-united-states-ec68656596a4

I can't guarantee I got everything correct, but I tried!

I did a paper on the early Ghana empire when I was in college, so I'm into it for that reason, too. But I've forgotten more than I remember.

Thanks for the Ghana info. Another source of research for me! :-)