West Africa is the region of western Africa generally considered to include these countries:
Cameroon, Cape Verde, Chad, Republic of the Congo (Congo-Brazzaville), Equatorial Guinea, Gabon, Mauritania, Sao Tome and Principe and Western Sahara are sometimes considered a part of West Africa.
Colonial boundaries as reflected in the modern boundaries between contemporary West African nations, cut across ethnic and cultural lines, often dividing single ethnic groups between two or more countries.
West Africa is an area with a great span of geography, bioregions, and cultures. It is oriented west of an imagined north-south axis, principally on what is known as the Bulge of Africa.
The southern and western borders of the region is the Atlantic Ocean. The northern border is the Sahara Desert, with the Niger Bend generally considered the northernmost part of the region. The eastern border is less precise. Some place it at the Benue Trough , others on a line running from Mount Cameroon to Lake Chad, others use the less precise border between Bantu and non-Bantu.
West Africa is divided into several distinct regions.
The northernmost band is the Sahel more arid than the Sudan and suitable only for grazing. It was long dominated by nomadic horsemen such as the Mande and Fulani who controlled much of West Africa from this base growing rich from the land trade across the Sahara.
South of the Sahel is the Sudan, a steppe-like region suitable to farming and pastoralism. It was thus a mix of settled peoples like the Hausa and Yoruba and the same nomadic groups that controlled the Sahel.
The southern most band is the coastal area known as Guinea. Portions of this coast were once known as the Grain Coast, the Gold Coast, the Slave Coast, the Pepper Coast, and the Ivory Coast. The slave trade was conducted heavily in this area; most African Americans are descended from slaves transported from West Africa.
The coast is largely tropical, and a belt of tropical moist broadleaf forests once followed the coast through most of this area. In earlier eras this was the poorest area as it was impossible to have livestock do to the many diseases in the region, most notably trypanosomiasis. A variety of plant diseases also limited agriculture.
This changed with new trade links through the Atlantic Ocean. Guinea had far more natural resources than the more arid plains. Once the forest was cleared the land was also far better for agriculture. Today it is far richer and more populated.
Historically, the area was home to several major African empires, including the Mali Empire, Songhai Empire, and the Ghana Empire. It was one of the world's great civilized regions, with the great city of Timbuktu being one of the most important centers of trade and learning in the Old World. Prosperous and culturally active states thrived in West Africa for many centuries, although a variety of forces including the slave trade and climactic change in West Africa led to these states' gradual decline.
Archaeological studies at Mejiro Cave have found that early human settlers, probably related to the Pygmies, had arrived in West Africa around 12,000 B.C.E. Microlithic stone industries have been found primarily in the region of the Savannah where fairly advanced pastoral tribes existed using chiseled stone blades and spears. The tribesmen of Guinea and the forested regions of the coast were without microliths for thousands of years, but prospered using bone tools and other means. In the fifth millennium, as the ancestors of modern West Africans began entering the area, the development of sedentary farming began to take place in West Africa, with evidences of domesticated cattle having been found for this period, along with limited cereal crops. Around 3000 BCE, a major change began to take place in West African society, with microliths becoming more common in the Sahel region, with the invention of primitive harpoons and fish-hooks.
Ancient West Africa included the Sahara, as the Sahara became a desert only since around 3000 BC (see Sahara). The Saharans are credited with the earliest accounts of shipbuilding, dating as early as 18,000 BC (see shipbuilding).
A major migration of Sahel cattle farmers took place in the third millennium BCE, and the pastoralists encountered the developed hunter-gatherers of the Guinea region. Flint was considerably more available there and made the use of microliths in hunting far easier. The migration of the Sahel farmers was likely caused by the final desiccation of the Sahara desert in this millennium, which contributed greatly to West Africa's isolation from cultural and technological phenomena in Europe and the Mediterranean Coast of Africa. Nevertheless, the increased use of iron and the spread of ironworking technology led to improved weaponry and enabled farmers to expand agricultural productivity and produce surplus crops, which together supported the growth of urban city-states into empires.
By 400 BCE, contact had been made with the Mediterranean civilizations, including that of Carthage, and a regular trade in gold being conducted with the Sahara Berbers, as noted by Herodotus. The trade was fairly small until the camel was introduced, with Mediterranean goods being found in pits as far south as Northern Nigeria. A profitable trade had developed by which West Africans exported gold, cotton cloth, metal ornaments, and leather goods north across the trans-Saharan trade routes, in exchange for copper, horses, salt, textiles, and beads. Later, ivory, slaves, and kola nuts were added to the trade.