Turkmenistan (also known as Turkmenia) is a Turkic country in Central Asia. The name Turkmenistan is derived from Persian, meaning "land of the Turkmen". Until 1991 it was a constituent republic of the Soviet Union, the Turkmen Soviet Socialist Republic. It is bordered by Afghanistan to the southeast, Iran to the southwest, Uzbekistan to the northeast, Kazakhstan to the northwest, and the Caspian Sea to the west. Eighty-seven percent of the population is Muslim. According to CIA World Factbook 2006 figures, Turkmenistan ranks 5th on the world according to GDP growth rate. Although it is wealthy in natural resources in certain areas, most of the country is covered by the Karakum (Black Sands) Desert. It has a single-party system and was ruled by President for Life Saparmurat Niyazov until 21 December 2006, when he died of cardiac arrest. Presidential elections were held on 11 February 2007. Gurbanguly Berdimuhammedow was declared the winner with 89% of the vote. He was sworn in on 14 February 2007.