The pedigree of the Venedotian kings is given in HG 1. However, this list poses a problem in terms of chronology until it is treated as two separate lines of descent, labelled HG 1a and HG 1b:
||CBa||HG 1b seg.
|4||Cadwaladr F.||Alain II|
|2||Cadfan||Hoel III||(Beli m. Rhun)|
|1||Iago||Alain I||Rhun Hir||Perweur|
|0||Beli||Hoel II||Maelgwn Gwynedd||Rhun R.|
|-1||Rhun||[Einion]||Hoel I||Cadwallon L.||Einion|
Although later sources show Merfyn Frych as the husband of Esyllt, a viewpoint supported by Bartrum, this earlier document is correct in stating he was her son. As can be seen in the second column, the list states that Rhun was the father of Beli. This is correct but that individual was not Rhun Hir, the son of Maelgwn Gwynedd, who appears in the fifth column above.
Rhun Hir married Perweur ferch Rhun Ryfeddfawr, whose name appears in ByA 28c, and they both belonged to gen. 1 as shown in the table. Triad 79 tells us she was one of the Three Lively Ladies of Britain. ByA 28c errs when it says Perweur was the “Mam Beli m Rhun …”. As can be seen from the second column Beli ap Rhun belonged to the same generation as his supposed parents. Brut y Brenhinedd confirms that Rhun was the father of Beli. Historia Regum Britanniae wrongly asserts that Einion was the father whereas in fact Einion Yrth was a grandfather. It was Rhun ap Einion Yrth and not Rhun Hir who fled to Armorica. His daughter, Tymyr, married Hoel II who appears in CB, see above table.
Both HRB and ByB correctly assert that Einion was Rhun’s brother. This allows us to solve a 1500 year old murder mystery which is not a whodunit but a “who was it dun to”, as we know the identity of the murderer but it is unclear who the victim was. Gildas wrote of Maelgwn:
In the first years of thy youth, accompanied by soldiers of the bravest, whose countenance in battle appeared not very unlike that of young lions, didst thou not most bitterly crush thy uncle the king with sword, and spear, and fire?
The Latin text uses the word “avunculus” where the above passage reads “uncle”. Strictly speaking, that term means mother’s brother. However, in this context I believe this can be linked to the fact, given in JC 23, that an Einion was half-brother to Cadwallon Lawhir, Maelgwn’s father, through their father Einion Yrth. Their mothers were sisters, daughters of king Didlet.
Although HRB states Rhun escaped to Armorica after the death of Einion because he was driven out by the Saxons, it would seem that Maelgwn had a hand in it as well. After Maelgwn’s death his son successfully thwarted challenges to his kingship. However, it would seem that the rightful lineage to the throne was reestablished when Iago became king. As can be seen in the above table, Cadwallon ap Cadfan is correct when he tells Salomon II in the ByB that their two fathers were two second cousins.