Population Growth in Ghana. Evidence from excavations, written texts, and oral histories indicates that the population of ancient Ghana increased from 300 through 1000. Growth rates differed from year to year—sometimes coming in major spurts, sometimes incrementally—based on territorial conquests, migration, and indigenous births. By the end of the tenth century, Ghana probably had more than two million residents living in a territory that covered more than 250,000 square miles. This empire was organized into a confederation of semi-autonomous chieftaincies and clan-based states that recognized the authority of the ruler (or tunka) and paid him tribute and/or taxes.

Feeding the Empire of Ghana. In order to feed this expanding populace and produce the surpluses needed for intraregional and interregional exchange, Ghana grew millet, sorghum, and rice for its starches, and used animal...