Archaeological evidence indicates that Georgia has been the site of wine production since at least 6,000 BC, which over time played a role in forming Georgia's culture and national identity. The classical period saw the rise of a number of early Georgian states, the principal of which were Colchis in the west and Iberia in the east. In Greek mythology, Colchis was the location of the Golden Fleece sought by Jason and the Argonauts in Apollonius Rhodius' epic tale ''Argonautica''. The incorporation of the Golden Fleece into the myth may have derived from the local practice of using fleeces to sift gold dust from rivers. In the 4th century BC, a kingdom of Iberia – an early example of advanced state organization under one king and an aristocratic hierarchy – was established.