Colchis was a region in the Southern Caucasus that appeared in the story of Jason and the Golden Fleece, in Greek mythology. It was on the area where modern-day Georgia is now located.
In the myth of the Argonauts, Jason was told to retrieve the Golden Fleece from Colchis by the king of Iolcus, Pelias, who had usurped the throne from his brother Aeson, who was Jason's father. Jason organised the expedition, and along with his shipmates, the Argonauts, set sail for Colchis. There, he told King Aeetes that he wanted to take the Golden Fleece, and the king accepted to help him if he passed a number of trials. Jason eventually succeeded to pass the trials and kill the never-sleeping dragon that guarded the fleece, and retrieved it. He then set sail for Greece, followed by Aeetes' daughter, Medea.
See Also: Jason, Argonauts, Golden Fleece, Pelias, Aeson, Pelias, Medea, Aeetes