West Africa is characterized by a large number of different peoples and languages. There are three broad bands of climate and cultures.

1) To the south are the rain forests, or what were rain forests before human development cut them down: countries wholly or partly in this band are Sierra Leone, Liberia, Ivory Coast, Ghana, Togo, Benin, southern Nigeria, southern Cameroon and further south. These were immune from the horse empires to the north because the horses died in the forests.
2) further north are lands with more open vegetation, the Savannah: Senegal, Guinea, Burkina Faso, northern Ivory Coast, northern Ghana, middle Nigeria, and other areas. These supported horse cultures able to conquer their neighbors and form empires.
3) the Sahel - a dry country with some vegetation and unreliable seasonal rain: northern Senegal, Mali, Niger, Chad, northern Nigeria. This was the northern edge of the horse cultures and the southern edge of the camel cultures. Trade routes carried gold to Europe across the real arid Sahara.
This area in general is believed to be the ancestral home of the black Africans. This is deduced from the existence of numerous language families and the degree of differentiation between languages. This is always a sign that a great deal of time has passed to allow divergences. It can be contrasted with the area of Bantu Africa where there are similarities of vocabulary and language structure across southern and eastern Africa showing that the people have migrated, probably from West Africa, within historical times, probably the last two millennia.

Diaspora
There is also a West African diaspora in the Americas. The culture of the blacks of north and south America includes elements from west Africa. Yoruba is still spoken in many of these countries, sometimes as a religious language, as in Cuba.

Did West Africans reach the Americas before Columbus? This is one of those topics historians are very cautious about. There is no firm evidence that either Africans or other Old World peoples crossed the Atlantic in numbers sufficient to make a difference to the cultures on either side. Fringe writers have proposed trans-Atlantic voyages by various peoples including Celts, Phoenicians, Egyptians, Welsh and Irish, as well as the generally accepted voyages of the Vikings. However, the evidence they present does not stand up to scholarly standards of verifiability. Olmec heads of Central America are said to have an "African appearance", but do they?

Also part of disputable history are early contacts from Indonesia. The Indonesians (linguistic evidence suggests from Borneo) who settled Madagascar may have sailed as far as West Africa. The evidence is said to be in the musical forms and instruments found in some parts of West Africa. Did the West Africans discover the cultivation of rice independently of Asians? This too is a fruitful area of debate, possibly to be settled by genetic analysis.

West Africa's trade across the Sahara is not disputed. Much of medieval Europe's gold is believed to have come from the gold fields of Ghana and Mali.