ancient region at the eastern end of the Black Sea south of the Caucasus, in the western part of modern Georgia. It consisted of the valley of the Phasis (modern Riuni) River. In Greek mythology Colchis was the home of Medea and the destination of the Argonauts, a land of fabulous wealth and the domain of sorcery. Historically, Colchis was colonized by Milesian Greeks to whom the native Colchians supplied gold, slaves, hides, linen cloth, agricultural produce, and such shipbuilding materials as timber, flax, pitch, and wax. The ethnic composition of the Colchians, who were described by Herodotus as black Egyptians, is unclear. After the 6th century BC they lived under the nominal suzerainty of Achaemenidian Persia and passed into the kingdom of Mithradates VI (1st century BC) and, then, under the rule of Rome.

United with Lazica in the 4th century AD, Colchis constituted an important buffer state between the Sāsānian and Byzantine empires. In the late 8th century Colchis was attached to Abasgia, which in turn was incorporated into Russian Georgia.