The forest zone of West Africa, in the strict sense, covers all of Liberia and Sierra Leone, most of Guinea, the southern halves of Côte d'Ivoire and Nigeria, and parts of Ghana, Togo and Guinea-Bissau.
The Dahomey Gap splits the forest zone into two halves by producing an area of much drier climate - Accra receives less than 760 millimetres (30 inches) of rainfall per year - between the wetter regions capable of supporting rainforest.
To the north, as the length for which the region is affected by the Intertropical Convergence Zone declines, the dry season becomes too long to support rainforest except in the wettest areas of the far west.
As this trough moves north and south, it creates two rainy seasons on the extreme southern coast: a heavy one between May and July and a lighter one in October and November.
Further west, due to the ancient geology of the region, soils are much less fertile and farming becomes chiefly confined to the raising of perennial crops, with cocoa remaining pre-eminent.
Whilst this region contains numerous large cities, the most important being Lagos, Ibadan and Port Harcourt, both of which have grown into mega-cities since the 1970s, the majority of its population remains rural and dependent upon subsistence farming.
The most famous is the pygmy hippopotamus (Hexaprotodon liberiensis), whilst the royal antelope (Neotragus pygmaeus) is one of the smallest hoofed mammals in the world and is remarkable for its ability to leap up to ten times its body size.