An ancient African kingdom we call Ghana existed in West Africa between the Niger and the Gambia Rivers from about 300CE to about 1100. The rivers were important to Ghana because its economy was based on trade. Before the modern age, rivers were the fastest way to carry goods. Ghana became wealthy by collecting taxes from traders who passed through the kingdom. The people called their nation Wagadu; we know it as Ghana because that was the name of their war chief.
Ghana managed the gold trade despite having few natural resources of its own. The gold and salt mines all lay beyond the borders of the empire, but the true power of Ghana was based on the superior skill of its people in working with iron. Ghanaian warriors used iron-tipped spears to subdue the neighbors, who fought with less efficient weapons made of stone, bone, and wood.
Muslim warriors known as Almoravids called a jihad (“struggle” in Arabic) on Ghana because the Ghanaian people kept their traditional beliefs and refused to accept Islam. The Almoravids were successful in weakening Ghana, but the empire continued to exist for more than a century. Many local warriors throughout the formerly mighty kingdom formed small states that threatened the vital trade routes through West Africa.