The tale of Tristan and Isolde is one of the most influential romances in the medieval period. It predated and influenced the Arthurian romance of Lancelot and Guinevere.

Originally, the Tristan legend had nothing to do with King Arthur, but shortly after the Vulgate Cycle (or Lancelot-Grail cycle) in c. 1235, the Prose Tristan, the hero had joined the fellowship of the Round Table.

There are two main traditions of the Tristan legend. The early tradition comprised of the romances from two French poets from the second half of the twelfth century – Thomas and Beroul. Their sources could be trace back to the original, archetype Celtic romance.

Later traditions come from the Prose Tristan (c. 1240), which was markedly different from the earlier tales written by Thomas and Beroul. The Prose Tristan became the official medieval tale of Tristan and Isolde that would provide the materials for Sir Thomas Malory, the English author, who wrote the Le Morte d’Arthur (c. 1469).