By size, population, and natural resources, Tim Marshall explains (in Prisoners of Geography: Ten Maps That Explain Everything About the World), Nigeria is West Africa’s most powerful country:
It is the continent’s most populous nation, with 177 million people, which, with its size and natural resources, makes it the leading regional power. It is formed from the territories of several ancient kingdoms that the British brought together as an administrative area. In 1898, they drew up a “British Protectorate on the River Niger” that in turn became Nigeria.
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In colonial times the British preferred to stay in the southwestern area along the coast. Their “civilizing” mission rarely extended to the highlands of the center, nor up to the Muslim populations in the north, and this half of the country remains less developed than the south. Much of the money made from oil is spent paying off the movers and shakers in Nigeria’s complex tribal system.
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The kidnapping of foreign oil workers is making it a less and less attractive place to do business. The offshore oil fields are mostly free of this activity and that is where the investment is heading.
The Islamist group Boko Haram, which wants to establish a caliphate in the Muslim areas, has used the sense of injustice engendered by underdevelopment to gain ground in the north.
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Most of the villages they have captured are on the Mandara mountain range, which backs onto Cameroon. This means the national army is operating a long way from its bases and cannot surround a Boko Haram force. Cameroon’s government does not welcome Boko Haram, but the countryside gives the fighters space to retreat to if required.