asides from west african kingdoms, there has been little development in africaI don't know about you saying Africans preferred peacefulness and foraging + farming though, that's clearly false and biased on your part.
for example, the africans living in the congo lived on top of immense natural resources. Had they wanted to conquer land, they would've easily been able to use it to their advantage. Tons of gold, rubber, iron, etc was easily acessible with just basic tools
but they were contempt living tribal life in the jungle, so they never advanced
also madagascar was right next to where bantus lived, yet the first people to arrive there were somalis and indonesian traders