When I began the prequel to The Coming Storm/A Convocation of Kings some of the research I'd done on Egyptian society for the Servant of the Gods series - particularly how influential the Nubians were - came into play with
some major characters. I knew there had to be other African cultures I hadn't learned about - especially knowing how much native history tended to be overlooked by European nations. (Forgive me for taking some liberties with those societies, not with the essentials, but combining them to further the story.)
It was a fascinating study. The architecture was astonishing and the art incredible. As luck would have it, Henry Louis Gates, Jr., did a wonderful program for PBS 'Africa's Great Civilizations'. If you get the chance and want to know more about ancient African societies, check out - http://www.pbs.org/weta/africas-great-civilizations/home/
Keep an eye on this space for when the prequel becomes available.
The Coming Storm - https://www.amazon.com/dp/B004WLOBG2
Servant of the Gods - https://www.amazon.com/dp/B005XMAOP6