The broadest groupings of linked ethnic units are regional. Britain ruled most of the area of present-day Nigeria as two protectorates from 1900 to 1914, the southern and northern protectorates each having separate regional administrations. These portions were joined finally under a single Nigerian colonÍÍÍÍial government in 1914. But they retained their regionally based authorities, divided after 1914 into three regional units. The announcement of their imminent demise by the first postcoup military government in 1966 helped to set off violent reactions in the north against southerners who had settled in their midst, contributing to the outbreak of civil war.

Within each of the major northern and southern regions, there were significant subregions that combined ethnicity, geography, and history. What is generally referred to historically as the south included a western Yoruba-speaking area, an eastern Igbo area (the "g" is softly pronounced), a midsection of related but different groups, and a set of Niger Delta peoples on the eastern and central coastal areas. The north was widely associated with the Hausa-speaking groups that occupied most of the region, but the Kanuri predominated in the northeast, with a belt of peoples between the two there were also important pastoral nomadic groups (mostly Fulani) that lived throughout the same region. In the middle belt (see Glossary) were congeries of peoples in an area running east-west in the hills, along the southern rim of the north, dividing it from the larger region of Nigeria's south. On its northern side, the middle belt shaded culturally into the Muslim north. In contrast, on the southern side, its peoples were more similar to those of the south.

Data as of June 1991