Nigeria , officially the Federal Republic of Nigeria, is a country in West Africa. It borders Niger in the north, Chad in the northeast, Cameroon in the east, and Benin in the west. Its southern coast is on the Gulf of Guinea in the Atlantic Ocean. Nigeria is a federal republic comprising 36 states and the Federal Capital Territory, where the capital, Abuja, is located. Lagos, one of the largest metropolitan areas in the world, is the largest city in Nigeria and the continent of Africa. Nigeria has been home to several indigenous pre-colonial states and kingdoms since the second millennium BC, with the Nok civilization in the 15th century BC marking the first internal unification in the country. The modern state originated with British colonialization in the 19th century, taking its present territorial shape with the merging of the Southern Nigeria Protectorate and Northern Nigeria Protectorate in 1914 by Lord Lugard. The British set up administrative and legal structures while practicing indirect rule through traditional chiefdoms. Nigeria became a formally independent federation on October 1, 1960. It experienced a civil war from 1967 to 1970, followed by a succession of democratically-elected civilian governments and military dictatorships, until achieving a stable democracy in the 1999 presidential election; the 2015 election was the first time an incumbent president had lost re-election. Nigeria is a multinational state inhabited by more than 250 ethnic groups speaking 500 distinct languages, all identifying with a wide variety of cultures. The three largest ethnic groups are the Hausa–Fulani in the north, Yoruba in the west, and Igbo in the east, together comprising over 60% of the total population. The official language is English, chosen to facilitate linguistic unity at the national level. Nigeria's constitution ensures freedom of religion and is home to some of the world's largest Muslim and Christian populations, simultaneously.