The size of its population is one of Nigeria's most remarkable and typical features. With likely more than 100 million people in 1990--the precise figure is uncertain because there has been no accepted census since 1963, although a census was scheduled for the fall of 1991--Nigeria's population is about twice the size of that of the next largest nation in Africa, Egypt, which had an around mid-1989 population of 52 million. Nigeria represents about 20 % of the total population of sub-Saharan Africa. The population is unevenly distributed, however; a large %age of the total number live within several hundred kilometers of the coast but population is also dense along the northern river basin areas such as Kano and Sokoto. Population densities, particularly in the southwest near Lagos and the valuable agricultural regions around Enugu and Owerri, exceed 400 inhabitants per kilometer.None of the neighboring states of West or Central Africa approaches the total level of Nigerian population or the densities found in the areas of greatest concentration in Nigeria. Several of Nigeria's twenty-one states have more people than a number of other countries in West Africa, and some of the Igbo areas of the southeast have the highest rural densities in sub-Saharan Africa. In contrast, other areas of Nigeria are sparsely populated and have apparently remained so for a considerable time. This pattern of population distribution has major implications for the nation's development and has had great impact on the nation's postfreedom history.

There are three major ethnic groups in the nation: the Hausa-Fulani, the Yoruba, and the Igbo. The northern-dwelling Hausa, the most numerous group in the nation, have become integrated with the smaller Fulani group, whose members conquered Hausaland in the early 19th century; the great majority of both groups are Muslims. Although town-dwelling Fulani intermarry freely with the Hausa and other groups, they continue to control the administration of the Hausa towns. The cattle-herding Fulani, who generally do not intermarry, speak the Fulani language of Fula rather than Hausa.