Chad – landlocked country in Central Africa. It is bordered by Libya to the north, Sudan to the east, the Central African Republic to the south, Cameroon and Nigeria to the southwest, and Niger to the west. Due to its distance from the sea and its largely desert climate, the country is sometimes referred to as the "Dead Heart of Africa". Chad is divided into three major geographical regions: a desert zone in the north, an arid Sahelian belt in the centre and a more fertile Sudanese savanna zone in the south. Lake Chad, after which the country is named, is the largest wetland in Chad and the second largest in Africa. Chad's highest peak is the Emi Koussi in the Sahara, and N'Djamena, the capital, is the largest city. Chad is home to over 200 different ethnic and linguistic groups. Arabic and French are the official languages. Islam is the most widely practiced religion. While many political parties are active, power lies firmly in the hands of President Déby and his political party, the Patriotic Salvation Movement. Chad remains plagued by political violence and recurrent attempted coups d'état (see Battle of N'Djamena (2006) and Battle of N'Djamena (2008)). The country is one of the poorest and most corrupt countries in the world; most Chadians live in poverty as subsistence herders and farmers. Since 2003 crude oil has become the country's primary source of export earnings, superseding the traditional cotton industry.