The regnal list of Glywysing

The kings of Glywysing were descended from King Arthur as indicated by JC20 12:

Gen. JC20 12a seg.
13 Morgan Hen
12 Owain
11 Hywel
10 Rhys
9 Arthfael
8 Ceingar
7 Maredudd
6 Tewdws
5 [Rhain]
4 Cadwgon
3 Cathen
2 Gwlyddien
1 Nowy
0 Arthur
-1 Pedr
-2 Cyngar

Morgan Hen died in the year 974. The LL tells us:

Morgan Hen son of Owain, King of Glamorgan, contemporary with Edgar, King of England …[1]

Edgar died a year later in 975. The father of Morgan, Owain, according to the ASC, accepted Athelstan as overlord in the year 926. Arthfael’s father is given by JC 9 as Gwriad ap Brochwel. His mother, Ceingar from Dyfed.

[1] Rees, W. J., 1840, 502