The Lancelot–Grail, also known as the Prose Lancelot, the Vulgate Cycle', or the Pseudo-Map Cycle, is a major source of Arthurian legend written in French. It is a series of five prose volumes that tell the story of the quest for the Holy Grail and the romance of Lancelot and Guinevere. The major parts are early 13th century, but scholarship has few definitive answers as to the authorship. An attribution to Walter Map is discounted, since he died too early to be the author. This cycle of works was one of the most important sources of Thomas Malory's Le Morte d'Arthur.
The Vulgate Cycle adds an intriguing dimension to the King Arthur tradition, perpetuating Christian themes by expanding on tales of the Holy Grail and recounting the quests of the Grail knights. During this period, material takes on even more historical and religious overtones with tales that include and deal both in the death of Arthur and Merlin (drawing all the way back to Nennius’ Historia Brittonum).
The Vulgate Cycle combines elements of Old Testament with the birth of Merlin, whose magical origins are consistent with those told by Robert de Boron, as the son of a devil and a human mother who repents her sins and is baptized. Merlin is transformed into a prophet and given the ability of seeing future events by God.
The work is divided into five sections. The last three were actually the first to be written, starting in the 1210s. The first two came later, around the 1230s.