It was thought that Tristan was the hero of the Picts:_Drostán. The names of Drest, Drust or Drostán are included in the list of kings who ruled from the sixth to the eighth century in the Scottish Lowlands, and over present-day Northumberland. Other Pictish sovereigns are called Talorc. Thus, Drest, filius Talorgen, was on the throne from 730 to 735. The Celtic literature of the twelfth century mentions a Drystan ab Tallwch (Drystan, son of Tallwch) and also one Essylt, wife of March. Can one therefore conclude that Drystan, son of Tallwch, is the legendary character descending from Drostán, son of Talorc, and that the word Drystan combined with Tallwch certifies the considerable age of a story which might be of Viking origin, and in which Tristan is represented as the guardian of the sacred young of the wild boars?
Given the fact that the Goidelic theories concerning the Pictish origins of Tristan recede in the face of topographic details provided by the geography of the dialects of Cornwall, it suffices to accept Tristan as a ruler over the Picts, before he enriched the legend of the Celtic countries under the Welsh name of Drystan._There is also a King Marc among the sovereigns of sixth-century Cornwall;_but there is no real evidence that he is the Marc of the legend.
Apparently it was the Welsh who introduced Tristan and King Marc in one and the same story.
As for the derivation of the name Isolt (Iseut, Esyllt, Ysolt, etc.), and the date of its appearance in the story, we are also short of satisfactory evidence.
However, just as traces or customs of the tenth century are easy to identify in the Chanson de Roland, equally the Tristan of the twelfth century preserves reminiscences or practices of a much earlier age. In addition to the obvious example of the Celtic 'arc Qui ne faut' (the 'bow Fail-naught'), we find also, in the palace of King Marc, a stream running through Isolt's room. Tristan announces his presence to Isolt by throwing chips of wood into the current which carries them to the point where Isolt can see them. King Marc's residence also hardly resembles a palace as it would be described by a twelfth-century narrator, a time in which feudal ceremony necessarily prevails over domestic simplicity. Even older literary reminiscences are evoked by Tristan's fight against the dragon, and the episode of the cut-out tongue, which resembles closely the victory of Perseus over Medusa, and the decapitation of the Gorgon. Perseus marries Andromeda, and Tristan wins Isolt for Marc.
The legend of Theseus completes these classical memories. In either case a tribute of young people is payable to Morhot, and to the Minotaur. Tristan, and Theseus each come forward alone to fight the monster; both succeed in their task. However, the most obvious analogy is perhaps the following: Theseus is suposed to hoist a white sail in case of victory; in the opposite case, a black sail. He forgets to change sails, and his father who is waiting for him, dies of grief when he sees the black sail.
Such similarities, and there are other and less obvious ones, confirm, of course, the presence of classical Greek tradition in the story of Tristan. But history reminds us that Edgar XII, King of England, in the year 961, changed the tribute of specie and cattle that the Welsh were bound to pay him each year, into a batch of 300 heads of wolves; also, that the same king reprieved a number of criminals on the condition that they delivered a number of wolves' tongues in proportion with the gravity of their crimes. Can one forget, in a field so close to teratology, that the Norman ships - drakkars - carried a dragon for a figurehead?...
Some scholars maintain that these themes are part of the heritage shared by the Greek, Celtic or Norse mythologies. Others, that the source of these legends is to be found at the very beginnings of Irish literature and in particular in the story of Diarmaid and Grainne with its abduction scenes (aitheda). Yet, more important is the fact that these analogies (Marc equipped with asses' ears like Midas, or marc which is the Celtic word for horse) have no impact on the crucial part of the story, which is the relationship between Isolt and Marc, and the consequences resulting from drinking the love potion. Analysing the sources of the Tristan legend, Pauphilet believes that there are nuclei of Celtic origin which may themselves represent a medley of earlier folk myths. He quotes the example of a legend from the Tochmarc Emere (The wooing of Emere) which tells about the hero who, on his way to Ireland, arrives at the dwelling of the King of the Isles, Ruad, at the very moment when the Irish go on shore to collect the tribute they demand. The hero learns that the King's daughter has been offered up to monstrous gods: the Fomore. The young girl is on the beach awaiting them. The hero joins her, fights the three monsters, and slays them;_but he is wounded by his last adversary.
The King's daughter dresses the wound with a shred from her garment, and the hero leaves her without revealing his identity. The girl tells her father the story. The King receives foreigners: the hero is among them. They all boast as best they can of having killed the Fomore.
The girl does not believe them. She has a bath prepared and recognises, by the wound of one of the guests, the man who saved her.
The King offers his daughter to the hero who prefers to arrange a meeting with the Princess, in Ireland, in a year's time
Having regained his strength, the hero tries to abduct Emere, but unsuccessfully until the date of the arranged meeting. He makes his way to the shore of Loch Cuan from where he notices two birds flying over the water. With his sling he brings down one of them. The birds, then, are transformed into two very beautiful women: the daughter of King Ruad and her attendant who are somewhat upset by this reception. With his lips the hero extracts the stone from the wound, then explains that he could not possibly marry the girl because he has drunk her blood, and he marries her to his foster brother.
The hero's name is Cu Chulainn, and for a companion he has a certain Drust whose presence is not explained in the story and who is otherwise unknown in this group of legends (there are, by the way, a number of parallel versions of the deeds of Cu Chulainn).
It has been suggested that this Drust was not a supernumerary, but indeed the main character in a lost saga, and that in the Tochmarc Emere, Drust is no more than a prop to the main story, if not simply an anachronism. In any case, it is interesting to see that a Drust (Drostán or the Drystan of the Welsh) is placed at the centre of adventures so remarkably similar to those of the Tristan story: the tribute, the fight with the monster, the healing of the wound, the scene in the bath, the identification of the victor, the reward and the refusal to accept it, the departure and the return of the chosen one, the sucking of the wound (primitive form of incest or love potion?), then the marriage to another woman.
Considering the limited extent of our knowledge, it is difficult to follow the gradual growth of the Tristan legend. One theory is that an Irish monk has woven incidents of classical mythology into a narrative made up of a sequence of lais (laíd or loíd) or poems which in the old Irish sagas set off the lyrical passages against the litany of the actual narration. These same sagas also inform us about the close, and lasting links between our earthly human world and the Other World, and the frequent interchanges taking place between the two: Gods and Fairies mingling with the crowds at seasonal Festivals, whereas Humans, sometimes victims of aitheda or under the spell of some charm or other (geis), depart for the Magic Islands of the Other World, only to be reached at the end of long voyages (imrama) or journeys underground as in the case of the subterranean kingdom of the Tuatha de Danann, elves who formerly lived in the Ireland of old, jealously guarding the traditions of ancient and obscure civilisations.
Whatever the exact age of the story of Tristan, one has to accept it in the first place as a collection of myths; myths of birds, for instance, who transform into women. This is a theme found in certain versions of the legend of the Grail story (the one of Esclarmonda among others), even if it does not occur explicitly in Beroul's Tristran where, however, King Arthur and his Knights enter the lists and also - even if the Members of the Flat Earth Society in London have not yet recanted - where'... la Table Ronde
... tornoie comme le Monde' (... the Round Table ... turns like the world).
It is therefore surprising to see the theme of the bird-woman eliminated in this context, perhaps because of its fairytale character, in a story in which even dragons enjoy such a vitality that no one would be surprised to meet them off the beaten track, as could happen to any visitor on the island of Komodo. Other original centre-pieces are probably the incident with the bird that drops the strand of golden hair onto Marc's sleeve and Isolt's arrival in Brittany when she rushes to the dying Tristan. She is so beautiful that the people, at the sight of her beauty, think that the Queen can be no one other than a sîde, in other words one of those ladies from the Other World, who according to the Celtic legend come this side in order to charm and seduce men; different from other women, they are sometimes betrayed by their floating blond hair and their mysterious as well as enchanting voices.