The second son of Mor/Mar was Arthwys c. 455 or 460, known as Arthur of the Pennines. Arthwys had two sons, St.Pabo Post Prydain c.470 – 530, whose daughter Arddyn Penasgell (Wing Headed) c.510 married Brochfael Ysgythrog of the family line.
The second son was Cynfelyn c.474. The next son of Mor was Morydd , who in turn fathered Morfryn Frych (the Freckled), who after marrying Alden was later to become a king in the Gwynedd area.
Ceneu’s second son Gwarst is known to have fathered two sons, Meirchion Gul (the Lean) c.422 and Masgwid Gloff c.444, King of Elmet. Meirchion Gul had three sons, which caused the Rheged kingdom to be split. The first was Cynfarch Oer (the Dismal) c.461, King of North Rheged, and the second Elidyr Llydanwyn (the Stout and Handsome) c.464. They married two sisters Nyfain and Gwawr, the daughters of Brychan. The third was Idno c.466 who had no offspring. Masgwid Gloff had five sons, Llaennog c.475, King of Elmet and his brothers Einion c.477, Arthwys c.479, St. Cynllo c.481 and Ceredig c.483, none of whom became kings or had family.