Uzbekistan is the most populous of the several countries to comprise the South Caucasus and Central Asia. It was the Uzbek Soviet Socialist Republic of the USSR from 1924 until 1991, when it gained its independence. Under Russian rule, the Uzbekistan capital of Tashkent tended to function as the commercial center of the region. Home to a multitude of ethnic groups, the majority group, the Uzbeks, descend from Turkic-speaking nomads and Persian-speaking inhabitants. Uzbekistan contains Central Asia’s oldest and most important cultural centers and their role in Islamic history was influential in the formation of intellectual movements and political empires. Islam has been the dominant cultural tradition since the invasion of the Arabs in the 8th century, and its mystical form of Sufism has influenced political and economic life.