The southern part of the country is made up of a low, largely desert coastal strip c.30 mi (50 km) wide; in N Eritrea there is a narrower, level coastal zone adjoining a ruggedly mountainous inland plateau (3,000–8,000 ft/914–2,438 m high). Most of the country supports only a sparse population of pastoral nomads. The central plateau, however, has many fertile valleys where settled agriculture is pursued. The inhabitants of Eritrea belong to several ethnic groups, primarily the Tigrinya, Tigre and Kunama, Afar, and Saho, each of whom has a distinct language. Arabic is also spoken. The population is about equally divided between Christians and Muslims; the Jehovah's Witnesses and other religious groups that the government has not granted recognition to have been persecuted.