The History of West Africa has been divided into its prehistory, the Iron Age in Africa, the period of major polities flourishing, the colonial period, and finally the post-independence era, in which the current nations were formed. West Africa is west of an imagined north–south axis lying close to 10° east longitude, bordered by the Atlantic Ocean and Sahara Desert. Colonial boundaries are reflected in the modern boundaries between contemporary West African states, cutting across ethnic and cultural lines, often dividing single ethnic groups between two or more states.

The prehistory of West Africa spans from the earliest human presence in the region until the emergence of the Iron Age in West Africa. West African populations were considerably mobile and interacted with one another throughout the population history of West Africa. Acheulean tool-using archaic humans may have dwelled throughout West Africa since at least between 780,000 BP and 126,000 BP. During the Pleistocene, Middle Stone Age peoples, who dwelled throughout West Africa between MIS 4 and MIS 2, were gradually replaced by incoming Late Stone Age peoples, who migrated into West Africa as an increase in humid conditions resulted in the subsequent expansion of the West African forest. West African hunter-gatherers occupied western Central Africa earlier than 32,000 BP, dwelled throughout coastal West Africa by 12,000 BP, and migrated northward between 12,000 BP and 8000 BP as far as Mali, Burkina Faso, and Mauritania.