In the mirabilia attached to Nennius's History Arthur is a mythical figure as remote and as elusive as he is in early Welsh poetry and triadic lore.  In them, as in the earliest Welsh poems, he is pre-eminently Arthur "the warrior," but he is known besides as the owner of a famous hound, and as the father of a son whose name had been given to one of the natural features of the country.  The first "marvel," in connection with which Arthur's name occurs, is in the region of Buelt, or Builth.  Here, we are told, is a mound of stones, on the top of which is one stone bearing the mark of a dog's foot.  This mark was made by Cabal, "the dog of Arthur the warrior" (Arthuri militis), when he was hunting "the boar Troit" (porcum Troit).  The pile of stones was put together by Arthur, and is called Carn, or the Cairn of, Cabal.  The marvel lay in the fact that, though men might come and carry away the top stone "for the space of a day and a night," the stone was invariably found in its proper place the next day... (King Arthur in History and Legend, Jones, 1914)