Back in 1960 Nigeria had just one state and three main regions: East, West and North. The first multiple states were created in 1967 (12 of them). Biafra conflict (which lasts till this day) occurred in early seventies. And in 1976 the number of states was increased to 19.
In the first half of nineties Nigeria got 30 states and presently it has 36 of them. Each state possesses a certain number of independence and self-governance power. This helps to unite the nation and appease the conflicts, evoking between many tribes inhabiting Nigeria territory.