Mauritania. Mauritania, formally the Islamic Republic of Mauritania, is a sovereign country in Northwest Africa. It is bordered by the Atlantic Ocean to the west, Western Sahara to the north and northwest, Algeria to the northeast, Mali to the east and southeast, and Senegal to the southwest. By land area Mauritania is the 11th-largest country in Africa and 28th-largest in the world; 90% of its territory is in the Sahara. Most of its population of some 4.3 million lives in the temperate south of the country, with roughly a third concentrated in the capital and largest city, Nouakchott, on the Atlantic coast. The country's name derives from Mauretania, the Latin name for a region in the ancient Maghreb. It extended from central present-day Algeria to the Atlantic. Berbers occupied what is now Mauritania by the beginning of the third century AD. Groups of Arab tribes migrated to this area in the late seventh century, bringing with them Islam, Arab...