Chretien left his poem unfinished, and we do not know how he intended to complete the adventures of his hero; but those writers who undertook the task, Wauchier de Denain, Gerbert de Montreuil and Manessier, carried it out with such variety of detail, and such a bewildering indifference to Chretien's version, that it seems practically certain that there must have been, previous to Chretien's work, more than one poem dealing with the same theme.
The Enfances story is omitted, and there are parallels with the German Parzival, with Wauchier de Denain and with Gerbert, while much is peculiar to the Perlesvaus itself.
Recent discoveries have made it practically certain that there existed, prior to the extant romances, a collection of short episodic poems, devoted to the glorification of Arthur's famous nephew and his immediate kin (his brother Ghaeris, or Gareth, and his son Guinglain), the authorship of which was attributed to a Welshman, Bleheris; fragments of this collection have been preserved to us alike in the first continuation of Chretien de Troyes Perceval, due to Wauchier de Denain, and in our vernacular Gawain poems. Among these "Bleheris" poems was one dealing with Gawain's adventures at the Grail castle,where the Grail is represented as non-Christian, and present s features strongly reminiscent of the ancient Nature mysteries.
Gawain, included in the continuation to Chretien's Perceval by Wauchier de Denain, and attributed to Bleheris the Welshman, who is probably identical with the Bledhericus of Giraldus Cambrensis, and considerably earlier than Chretien de Troyes.
Another continuation by Gerbert, interpolated between those of Wauchier and Manessier, relates how the Grail was brought to Britain by Perceval's mother in the companionship of Joseph.
36614, we find the first continuator of the Perceval, Wauchier de Denain, quoting as authority for stories of Gawain a certain Bleheris, whom he states to have been "born and bred in Wales."