evidence: Cameroon, officially the Republic of Cameroon, is a unitary republic of central Africa. It borders Nigeria, Chad, Central African Republic, Republic of Congo, Gabon, Equatorial Guinea and the Gulf of Guinea. Cameroon, a German colony at the time of World War I, was split among the French and British as war spoils after the defeat of Germany. In 1960, French Cameroun became independent as the Republic of Cameroun, and merged with the southern part of British Cameroons in 1961 to form the Federal Republic of Cameroon. It was renamed the United Republic of Cameroon in 1972, and the Republic of Cameroon or République du Cameroun in 1984 (its official languages are English and French). [...] The country has four patterns of drainage. In the south, the principal rivers—the Wouri, Sanaga, Nyong, and Ntem—flow southwestward or westward directly into the Gulf of Guinea. The Dja and Kadeï, however, drain southeastward into the Congo River. In northern Cameroon, the Benoué River (Benue) runs north and west, eventually into the Niger, while the Logone River flows northward into Lake Chad. [...] Some of the borders of Cameroon follow rivers, including the Aïna River and Ntem River.