Tyro was married to King Cretheus of Iolcus, with whom she had three sons, Aeson, Pherês, and Amythaon, but she loved Enipeus, a river god.

One day, Poseidon, filled with lust for Tyro, disguised himself as Enipeus and lay with her; from their union were born twin sons, Pelias and Neleus.

Jason grew in the care of Chiron the centaur, on the slopes of Mount Pelion, to be educated while Pelias, fearing that he would be overthrown, was warned by an oracle to beware a man wearing one sandal.

Though the Golden Fleece simply hung on an oak tree, this was a seemingly impossible task, as an ever-watchful dragon guarded it.

[7] Jason made preparations by commanding the shipwright Argus to build a ship large enough for fifty men, which he would eventually call the Argo.

Aeëtes demanded that Jason must first yoke a pair of fire-breathing bulls to a plough and sow dragon's teeth into the earth.

Medea, daughter of Aeëtes, fell in love with Jason, and being endowed with magical powers, aided him in his completion of the difficult task.

[8] During Jason's absence, Pelias thought the Argo had sunk, and this was what he told Aeson and Promachus, who committed suicide by drinking poison.