The thirteenth century was one of the most fruitful periods in the history of medieval narrative fiction. It was not only the time when the twelfth-century Arthurian and Tristan verse romances were turned into prose, but when previously unconnected themes were adapted to form parts of larger cycles. Robert de Boron who himself wrote in verse at the end of the twelfth or the beginning of the thirteenth century, and who inherited on the one hand from Geoffrey of Monmouth and Wace the stories of Merlin and Arthur's kingdom, and on the other hand from Chrétien de Troyes the theme of the Grail, was the first writer to endeavour to combine these themes into a coherent narrative. Of Robert's verse romances, conceived as a trilogy, only the first part, the early history of the Grail, known as the Joseph or Le Roman de l’Estoire du Graal, and the beginning of the second part, the Estoire de Merlin, have been preserved in their original verse form. There is no evidence that Robert himself ever wrote a ‘third’ part, but shortly after the composition of the first two they were reworked in prose and in two of the prose manuscripts of the Joseph-Merlin the latter is followed by a third section, the so-called Didot Perceval, which is an account of Perceval's quest for the Grail followed by an account of Arthur's death, composed by a writer closely acquainted not only with Robert's Joseph-Merlin, but also with Chrétien's Conte du Graal and its First Continuation, as well as Geoffrey's and Wace's accounts of the final years of Arthur's reign.

Although one of Chrétien's romances centres on Perceval's search for the Grail and another of his works deals with a portion of Lancelot's life (Le Chevalier de la Charrette), Chrétien did not attempt to combine the themes of Lancelot and Guinevere with that of the Grail; and while Robert de Boron and his anonymous continuator, the author of the Didot Perceval, linked the themes of the Grail, Merlin, and Arthur, they did not bring into their work the story of Lancelot. It was the writers of the thirteenth-century Vulgate Cycle of Arthurian Romances (or Lancelot-Grail Cycle) who for the first time assigned an important function to the Lancelot-Guinevere story in the Arthur-Merlin-Grail complex.