Ghana was once called as the Gold Coast. Ghana still has a gold reserve that has been replaced by cocoa as the country's main source of income. Thus, Ghana is one of the world's largest producers of cocoa. Lake Volta is the world's largest artificial lake. About half of the Ghanaians are Ashanti people and other groups include the Mole, Dagbani, Ewe and Ga and the languages they speak are English, Akan, Mossi, Ewe, Ga, Twi, Fanti and Gurma. The ancestors of the Ashanti groups developed one of the richest and famous civilizations in Africa. The Ghanaians currency is called Cedi. A popular food in Ghana is banku, a mixture of maize dough and cassava.