Algeria, officially The People's Democratic Republic of Algeria, is a country in the Maghreb region of North Africa on the Mediterranean coast. Its capital and most populous city is Algiers. With a total area of 2,381,741 square kilometres, Algeria is the tenth-largest country in the world, and the largest in Africa and in the Mediterranean. The country is bordered in the northeast by Tunisia, in the east by Libya, in the west by Morocco, in the southwest by Western Sahara, Mauritania, and Mali, in the southeast by Niger, and in the north by the Mediterranean Sea. The territory of today's Algeria was the home of many ancient prehistoric cultures, including Aterian and Capsian cultures. Its area has known many empires and dynasties, including ancient Berber Numidians, Phoenecians, Lybio-Punic Carthaginians, Romans, Vandals, Byzantines, Arab Umayyads, Arab Abbasids, Arab Fatimids, Berber Almoravids, Berber Almohads, Turkish Ottomans and the French colonial empire. Algeria is a semi-presidential republic, it consists of 48 provinces and 1541 communes. With a population of 37.9 million, it is the 35th most populated country on Earth. Abdelaziz Bouteflika has been the President of Algeria since 1999 and has won four consecutive elections. However, according to the Democracy Index Algeria is an authoritarian regime.Algeria's economy is largely based on hydrocarbons, due to which manufacturing has suffered from Dutch disease. The country supplies large amounts of natural gas to Europe and energy exports are the backbone of the economy. According to OPEC Algeria has 17th largest reserves of oil in the world, and second largest in Africa, while it has the 9th largest reserves of natural gas. Sonatrach, the national oil company, is the largest company in Africa. Algeria has the second largest military in North Africa with the largest defense budget in Africa. Algeria had a peaceful nuclear program since the 1990s. Algeria is a member of the African Union, the Arab League, OPEC and the United Nations, and is a founding member of the Arab Maghreb Union.