The empires of Ghana, Mali, and Songhai controlled West Africa between A.D. 1000 and 1500. Each empire thrived on the trade of goods across the Sahara and was affected by the exchange of culture and belief systems along the trade routes. As each empire declined, the next empire took its place. Many great kings led these empires—for example, Mali's Mansa Musa—and they helped spread West African culture and resources around the world. One such resource was gold.