Also, one point that's not brought up often is that ancient african societies, like their european counterparts, engaged extensively in free trade, which contributed to their prosperity. The region's economic decline largely began when many of these societies shifted away from trade-based systems and adopted forms of proto-proto-communism. 

 Right, before extensive bureaucracy we had more liberties and free markets around the world. Free commerce used to be the default experience, with the local warlord taxes of course.