Niger is one of the largest inland countries in West Africa and is historically a gateway between North Africa and sub-Saharan Africa. With two-thirds of the country lying within the Sahara Desert, it is one of the hottest countries in the world. Niger is mostly a vast plateau, with an average elevation of 500 m, with low local relief. In the Sahelian zone of the country, the climate becomes semiarid and the vegetation cover increases. The central part of Niger is dominated by an extensive pastoral zone — mostly steppes or short grass savannas with shrubs and sparsely scattered trees. Most of the people derive their income from agriculture and stock raising and are highly vulnerable to periodic droughts and desertification. Moreover, land potential for agriculture is very unevenly distributed among Niger’s regions, with the southern regions providing nearly 98 percent of the arable land. The Niger River, for which the country is named, nourishes a ribbon of life as it flows about 550 km through western Niger. The river is the main source of freshwater and an important part of the economy through transportation and irrigation. Niger is a leading producer of uranium and is rich in many other minerals.