The Sudanic Environment

The West African Sudan refers to the broad expanse of savanna or tropical grassland lying south of the Sahara between the Atlantic Ocean and Lake Chad. This extensive geographical zone is essentially a great plain characterized by lightly wooded rolling terrain. Most of the savanna lies below 1500 feet above sea level, and exceeds 4000 feet only in the highlands of modern Guinea and Cameroon and in the central Nigerian Jos Plateau. In these highlands the headwaters of the major river systems of the Western Sudan are formed: the Gambia, Senegal, and Niger rise in the Guinea highlands; the Benue and its tributaries flow out of the Nigerian plateau and the Cameroon mountains.

The geography and history of the Western Sudan have been influenced to a considerable degree by its climate. The winds of the annual monsoon bring alternating dry and wet seasons to the savanna. Dust-laden northeast winds from the Sahara-the harmattan – prevail during the dry season between October and April, and the moist southwest monsoon from the Gulf of Guinea brings up to sixty inches of rainfall between May and September. The northern savanna experiences a longer dry season and receives less rainfall than the south; and the grassland gradually turns to dry steppe or sdhel before yielding to the true desert. In the southern latitudes, where a longer wet season and heavier rainfall support denser vegetation, moist woodlands give way to tropical rain forest along the Guinea coast.

In historical times the pattern of human life in the Western Sudan has been governed by this alternation of seasons. During the wet season the sedentary population practiced agriculture for local consumption and commercial exchange.