The Harleian MS. 3859 Genealogies are genealogies found along with the Historia Brittonum in Harleian MS. 3859 and are the oldest surviving Welsh genealogies of any extent. The genealogies begin with the line culminating in Owain son of Hywel Dda on his father’s side and mother’s side and so were probably compiled during his reign. The pictorial genealogies below are from this genealogical data. Probable corrections (in parentheses) are from P. C. Bartrum (pp. 9–13).