Well it depends what you mean by African? If you mean Black African(ie Sub Saharan africa) then there were some powerful kingdoms and smallish short lived Empires, but they had little impact on world history and were not very advanced.
There were Empires based in Non Black/North Africa....the Egyptians and Carthaginians had empires, as did the Moors later on.
However the Egyptians, Carthaginians and Moors were Semitic or Hamitic races and not Black Africans.
The main reason why Sub Saharan Africa did not really create any large Empires is that this part of the world was never technologically very advanced....unlike Mesopotamia, Egypt, Asia Minor, Greece, Rome, China, India etc....the Africans never developed advanced agriculture, military technology, built large cities and fortresses, they were also cut off from the rest of the world by geography, so they did not have the opportunity to learn from other peoples.