West Africa can be divided into three agro-ecological zones or three different trade basins (West Basin, Central Basin and East Basin). Both important for understanding market behavior and dynamics.
The three major agro-ecological zones are the Sahelian, the Sudanese and the Coastal zones where production and consumption can be easily classified. (1) In the Sahelian zone, millet is the principal cereal cultivated and consumed particularly in rural areas and increasingly, when accessible, in urban areas. Exceptions include Cape Verde where maize and rice are most important, Mauritania where sorghum and maize are staples, and Senegal with rice. The principal substitutes in the Sahel are sorghum, rice, and cassava flour (Gari), the latter two in times of shortage. (2) In the Sudanese zone (southern Chad, central Nigeria, Benin, Ghana, Togo, Côte d'Ivoire, southern Burkina Faso, Mali, Senegal, Guinea Bissau, Serra Leone, Liberia) maize and sorghum constitute the principal cereals consumed by the majority of the population. They are followed by rice and tubers, particularly cassava and yam. (3) In the Coastal zone, with two rainy seasons, yam and maize constitute the most important food products. They are supplemented by cowpea, which is a significant source of protein.