Gerald of Wales´s Descriptio Kambriæ records the descent of the rulers of South Wales in reverse chronological order as follows: “...Theodorus filius Cadelh, Cadelh filius Eneæ..., Eneas filius Oenei, Oeneus filius Hoeli da, id est Hoeli boni, Hoelus filius Cadelh, Cadelh filius Roderici magni”. 1
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Cadell co-ruled in Deheubarth from 1005 to 1018.
"After the death of MAREDUDD AB OWAIN, his combined kingdoms were ruled by CYNAN AP HYWEL until his own death in 1005. Edwin and Cadell, the sons of Maredudd's brother Einion, managed to reclaim some of the lands in Deheubarth. They were aggressive brothers who had sought to gain a share of the kingdom from the earliest opportunity, challenging Maredudd for territories in southern Wales in 991 and 994. Their hold on authority was tenuous and they were challenged by Aeddan ap Blegywryd, a usurper of uncertain origin.... Aeddan succeeded in deposing Edwin and Cadell. Their exact fate is unknown, and they may have been killed at this time, for they are not mentioned in any later records." 2
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In his scholarly History of Wales, Professor John Lloyd declined to discuss events in Deheubarth after the 999 death of Maredudd ap Owain, with this observation:
After Gwynedd was regained by Cynan ap Hywel ap Ieuaf in the year 1000 "a veil falls over the history of Deheubarth which suggests the beginning of a period of anarchy unexampled even in that turbulent age."
By process of elimination, we can get a reasonable idea of who succeeded Maredudd as king of Deheubarth in 999. He had no legitimate son, Cadwallon ap Maredudd having died in 992 as a youngster. While he had two daughters, one married to Llawr ap Aelan of Dyfed and the other not yet 10 years old, there was no reason for the men of Deheubarth to consider selecting a new king only maternally related to the Royal Family; Maredudd had a nephew, Edwin ap Einion, who was not only old enough for kingship but a son of the senior line of descent from Hywel Dda. Maredudd had represented a junior line and he had only been made king in 988 because the sons of his older brother, Einion, were then still teenagers or younger.
The eldest of those sons, Tewdwr ap Einion, was killed in 994 during the battle in which his uncle Maredudd was expelled from Gwynedd. The youngest brother, Cadell ap Einion, was yet in his early 20's. But Edwin ap Einion had become of full age for kingship about 998/999 and may well have been complicit in his uncle's death. As the heir holding the best claim to kingship, we should expect that claim was both asserted and upheld.
Little is known of the life or reign of Edwin. His mother had been a lady of Mercia and his eldest son, Hywel, also married a Saxon princess; we aren't told who Edwin married, but a preference for ladies born east of Wales did run in this family. His brother, Cadell, married a Powys lady, Elinor ferch Gwerystan, a sister of Cynfyn.* It might be significant that neither apparently chose a lady of Deheubarth. 3
* Cadell's marriage is cited in Bodleian Add. C-178, 25