King Arthur is seen by many as a semi legendary figure who embodies many older tales. In 'Brigantia, Cartimandua and Gwenhwyfar' Michelle Ziegler draws parallels between Arthur, Guinevere and Lancelot and the Brigates of the 1st cent. AD, their king, Venutius, his queen Cartimandua and her lover Vellocatus. You may recall that Cartimanuda was the one who handed Caractacus over to the romans. It is not unusual for later story tellers to recall older stories but change the names and the times.