Yes, I'm aware it's a broad topic. "European History" is a broad topic as well, but an overview can still be taught in a single high school AP class.
The book "Cultural Atlas of Africa" by Jocelyn Murray has a brief political history of every nation in Africa, after they became independent. It also covers the Scramble for Africa and modern social problems that bedevil Africa. It is weak on the pre-colonial history of Africa. My biggest disappointment with this book is that it barely mentions the pre-1500 kingdoms of sub Sahara Africa.