Tunisia has a highly irregular coastline that affords many bays and several fine harbors, notably Bizerte, Qabis, Safaqis, and Susah. Part of the Atlas Mts. runs through N Tunisia; but, unlike Morocco and Algeria, the mountains in Tunisia rarely exceed 4,000 ft (1,219 m) in elevation. In the south, below the Chott Djerid (a great salt lake), stretches the Sahara Desert. The population, which is largely Berber and Arab, lives mainly near the coast, in urban areas. Most Tunisians are Sunni Muslims; there is a small Jewish community dating back to ancient times, although most have emigrated to Israel or France. Tunisians of all backgrounds have migrated to France in significant numbers. Arabic is the official language, but French also is spoken.