I dont see any acknowledgement on any kingdoms concerning that in Africa here on AH.com, but there has been past examples in history such as Zimbabwe or Ethiopia, but in the entire continent the only kingdoms that I ever noticed that emerged were until the Renaissance, that of the Mali, Songhai, Congo, etc and those of Swahili Merchant Empires.
But is there anyway to have these kingdoms reach a technological civilization with of Europe in the Medieval Ages? This is actually concerning probably my TL because I want to cover this but in an earlier time.