It took place in time span of less than three years. The civil war in Nigeria lasted from July 6, 1967 till Januari 1970. Biafra in the south east corner of the country tried to move away from the country Nigeria and start a country on their own. The people did not feel part of the larger country, with boundaries coming from a different age and a different constellation.
Wole Soyinka revisits the days of Biafra and the present days of a longing for a separate state. You can read his article here.