I wasn't replying to you, just contributing to the thread.
No expert in African history here, but if there any parallels, I would link those with the great pre-Colombian civilizations. The Aztecs had a highly centralized state combined with a theocratic system, together with an advanced system of education and public service, which used slave labour and went to war for it as well.
I wish I could offer a deeper insight on those matters, but then again, I am no scholar of African kingdoms. The little I know show that they were sophisticated governments as any we find around the world, the difference being that they are not complex in a Western manner, which a lot of people think it is the only form of sophistication that matters.
The problem is that the complexity of these societies are many times exaggerated for political reasons. Like when people say the Papuan Kula exchange was complex - yes, it was complex, but it was nowhere near as complex as Western commerce. In other words, sophistication is necessarily relative.
In any case, even if they have thoroughly complex forms of organization - if those forms of organization weren't States or State-like, then they shouldn't be in the game as States.