There was no "written word" in sub-Saharan Africa pre-European liberation and their best civilisations were just sprawls of mud huts, with mud walls if they were particularly sophisticated. "Great". Nothing "great" about them. None of them advanced beyond the stone age. This picture of Renaissance Wakanda comes up first when I search for the "Great Walls of Benin" - ...optimistic.

I feel sorry for them, everyone needs a civilizational history to be proud of. That's why so many of them are so easily manipulated to want to destroy ours.