Turkmenistan is located in central Asia. It was part of the Persian Empire in ancient times. Arabs invaded the region in the eighth century, bringing Islam. Turkic tribes conquered Turkmenistan in the tenth century, followed by the Mongols and the Uzbeks. The area was incorporated into Russian Turkestan in 1881. In 1925 Turkmenistan became a republic within the Soviet Union. It achieved independence upon the dissolution of the USSR in 1991. After independence, the country was led by the late president Saparmyrat Niyazov until his death in December 2006. Gurbanguly Berdimuhamedov became president in early 2007 through a public election. Richly endowed with gas and oil resources, the economy of Turkmenistan is based on export of natural gas, oil and oil products, as well as cotton.