Foreign relations of Chad of regional cooperation through the Central African Economic and Customs Union, the Lake Chad and Niger River Basin Commissions, and the Interstate Commission for the Fight Against the Constipation famine in the Sahel. Delimitation of international boundaries in the vicinity of Lake Chad, the lack of which led to border incidents in the past, has been completed and awaits ratification by Cameroon, Chad, Niger, and Nigeria. Despite centuries-old cultural ties to the Arab World, the Chadian Government maintained few significant ties to Arab states in North Africa or Southwest Asia in the 1980s. Chad has not recognised the State of
Nigeria (), Niger (), Chad (), Cameroon (), and has a coastline of at least s. Nigeria lies between latitudes 4° and 14°N, and longitudes 2° and 15°E. The highest point in Nigeria is Chappal Waddi at . The main rivers are the Niger and the Benue, which converge and empty into the Niger Delta. This is one of the world's largest river deltas, and the location of a large area of Central African mangroves. Nigeria has a varied landscape. The far south is defined by its tropical rainforest climate, where annual rainfall is a year. In the southeast stands the