The cause of all this change is obvious. The age of Chivalry had come, and the Arthurian stories provided “the raw material” exactly suited to its romantic literary requirements. The original Celtic legends concerning Arthur and his few primitive “knights” lent themselves, at once, to adaptation and embellishment by writers whose main concern was with knight-errantry and courtly love; while the conception of an Arthurian “court,” with its fellowship of questing knights, invited the importation into it of any and every legendary hero whose story could in any plausible way be connected with Arthur. They had another advantage which contributed to their supreme popularity in the twelfth and the thirteenth centuries. They had about them an element of mystery, of magic, of indefiniteness, coming as they did from the Celtic wonderland in the West. The Arthurian kingdom had no geography,--it was a “no man’s land,” which defied all cartography, and the bounds of which could be extended by each romantic writer at his will. It is true that British tradition, and the bards and chroniclers who had sought to give it literary form, associated Arthur’s name with well-known localities in Great Britain; but, even there, the “champion of Britain” had no settled capital or court. London, the chief city of the Norman kings, claimed him as her own; but so did Winchester, Lincoln, York, Chester and Carlisle. Then there was Caerleon-upon-Usk, the delectable “metropolitan city” where Geoffrey of Monmouth had definitely located his court in Wales. Moreover places in Britain with mysterious legendary associations came to be connected with Arthur’s name. Glastonbury, whither Joseph of Arimathea was fabled to have brought the Holy Grail, was reputed to be his burial-place, and the district around it was identified with the mythical Avalon. The grim old western castle of Tintagel was fixed upon as his birthplace, and the tale of the battle on the Camel led to the building, in poetic imagination,[94] of a new Arthurian court at “tower’d Camelot.” The name of Camelot at once suggests such purely romantic regions as “the wild woods of Broceliande” and “the sad sea-sounding wastes of Lyonesse.”[95] Astolat, Cameliard, Sarras, Carbonek, Joyous Gard, and other places, belong to the same romantic class, and lie quite beyond geographical identification. Stories, in which the characters thus roamed indifferently among places well known to Norman England and in regions which belonged entirely to “the land of phantasy and illusion,” lay open to the incursion of fabulous matter drawn from many varied sources. In a word, the unrivalled possibilities of “the matter of Britain” for all kinds of romantic exploitation established for it an easy supremacy over the other romantic themes, and the literary uses to which it was put by writers of romance throughout Western Europe all but robbed it, ultimately, of its distinctive features as a native British growth.