The document summarizes the major West African trading kingdoms that developed between 400-1500 AD along the trans-Saharan trade routes. It discusses the Kingdoms of Ghana, Mali, and Songhai which controlled the salt and gold trades between Northern Africa and the tropical forest regions. It also mentions the city-states of Ile-Ife and Benin in the forest region which grew wealthy through gold trading but were not Islamic. The empires rose to power by controlling the trade routes but later declined from invasions or internal weaknesses.