The Huns were a nomadic group of people who are known to have lived in Eastern Europe, the Caucasus, and Central Asia between the 1st century AD and the 7th century. They were first reported living east of the Volga River, in an area that was part of Scythia at the time; the Huns' arrival is associated with the migration westward of a Scythian people, the Alans. They were first mentioned as Hunnoi by Tacitus. In 91 AD, the Huns were said to be living near the Caspian Sea and by about 150 had migrated southeast into the Caucasus. By 370, the Huns had established a vast, if short-lived, dominion in Europe.