Sanctus, Xantus of Cereticu
In Historia Regum Britanniae, there is a section that relates the story of a prince named Sant or Sanctus. According to the legend, Sant was the son of Ceredig, the ruler of Ceredigion (Cardiganshire) in Wales.
In Geoffrey’s version of the story, Sant is described as a noble and pious man who becomes a hermit after he is visited by an angel who tells him that his son will become a great saint. Sant’s son David is later born, and he goes on to become a bishop and the patron saint of Wales.
Saint David was said to be an uncle av King Arthur, according to Geoffrey. Other manuscripts makes him Arthur’s grand-nephew, and his second cousin.
See also
Sant | The Legend of King Arthur
Source
Historia Regum Britanniae | Geoffrey of Monmouth, c. 1138