The Federal Republic of Nigeria /naɪˈdʒɪəriə/, commonly referred to as Nigeria, is a federal constitutional republic in West Africa, bordering Benin in the west, Chad and Cameroon in the east, and Niger in the north. Its coast in the south lies on the Gulf of Guinea in the Atlantic Ocean. It comprises 36 states and the Federal Capital Territory, where the capital, Abuja is located. Its largest cities include: Lagos, Kano, Ibadan, Benin City and Port Harcourt. Nigeria is officially a democratic secular country. Modern-day Nigeria has been the site of numerous kingdoms and tribal states over the millennia. The modern state originated from British colonial rule beginning in the 19th century, and the merging of the Southern Nigeria Protectorate and Northern Nigeria Protectorate in 1914. The British set up administrative and legal structures whilst practising indirect rule through traditional chiefdoms. Nigeria became a formally independent federation in 1960, and plunged into a civil war from 1967 to 1970. It has since alternated between democratically-elected civilian governments and military dictatorships, until it achieved a stable democracy in 1999, with the 2011 presidential elections considered the first to be reasonably free and fair. Nigeria is often referred to as the "Giant of Africa", owing to its large population and economy. With approximately 184 million inhabitants, Nigeria is the most populous country in Africa and the seventh most populous country in the world. Nigeria has one of the largest populations of youth in the world. The country is viewed as a multinational state, as it is inhabited by over 500 ethnic groups, of which the three largest are the Hausa, Igbo and Yoruba; these ethnic groups speak over 500 different languages, and are identified with wide variety of cultures. The official language is English. Nigeria is divided roughly in half between Christians, who live mostly in the southern part of the country, and Muslims in the northern part. A minority of the population practise religions indigenous to Nigeria, such as those native to Igbo and Yoruba peoples. As of 2015, Nigeria is the world's 20th largest economy, worth more than $500 billion and $1 trillion in terms of nominal GDP and purchasing power parity respectively. It overtook South Africa to become Africa's largest economy in 2014. Also, the debt-to-GDP ratio is only 11 percent, which is 8 percent below the 2012 ratio. Nigeria is considered to be an emerging market by the World Bank; It has been identified as a regional power on the African continent, a middle power in international affairs, and has also been identified as an emerging global power. Nigeria is a member of the MINT group of countries, which are widely seen as the globe's next "BRIC-like" economies. It is also listed among the "Next Eleven" economies set to become among the biggest in the world. Nigeria is a founding member of the Commonwealth of Nations, the African Union, OPEC, and the United Nations amongst other international organisations. In the 2014 ebola outbreak, Nigeria was the first country to effectively contain and eliminate the Ebola threat that was ravaging three other countries in the West African region, as its unique method of contact tracing became an effective method later used by other countries, such as the United States, when Ebola threats were discovered. Since 2002, the North East of the country has seen sectarian violence by Boko Haram, an Islamist movement that seeks to abolish the secular system of government and establish Sharia law across Nigeria. Nigerian President Goodluck Jonathan in May 2014 claimed that Boko Haram attacks have left at least 12,000 people dead and 8,000 people crippled. At the same time, neighbouring countries, Benin, Chad, Cameroon and Niger joined Nigeria in a united effort to combat Boko Haram in the aftermath of a world media highlighted kidnapping of 276 schoolgirls and the spread of Boko Haram attacks to these countries.