The country consists of a coastal lowland in the south, a densely forested plateau in the interior, and a region of upland savannas in the north. Rainfall is heavy, especially along the coast. There are over 60 ethnic groups in Côte d'Ivoire; the major groups are the Baoule, Beti, Senufo, Malinke, Anyi, and Dan. There are also a significant number of immigrants from neighboring Burkina Faso, Mali, and Guinea, as well as many people of Lebanese and French descent. The population is about 40% Muslim, with some 35% following traditional religious beliefs, and 25% Christian. The Muslims predominate in the north, while Christians are concentrated in the south. French is the official language. There are also some 60 native dialects, with Dioula the most widely spoken.