Nigeria was amalgamated in 1914, only about a decade after the defeat of the Sokoto Caliphate and other Islamic states by the British which were to constitute much of Northern Nigeria. The aftermath of the First World War saw Germany lose its colonies, one of which was Cameroon, to French, Belgian and British mandates. Cameroon was divided in French and British parts, the latter of which was further subdivided into southern and northern parts. Following a plebiscite in 1961, the Southern Cameroons elected to rejoin French Cameroon, while the Northern Cameroons opted to join Nigeria, a move which added to Nigeria's already large Northern Muslim population. The territory comprised much of what is now Northeastern Nigeria, and a large part of the areas affected by the present and past insurgencies.
Following the return of democratic government in 1999, the Muslim-dominated northern Nigerian states have introduced Sharia law, including punishments against blasphemy and apostasy. Several incidents have occurred whereby people have been killed for or in response to perceived insults to Islam.