ANCESTRY OF CYNAN TYNDAETHWY
By Darrell Wolcott
Cynan Tyndaethwy was the
last king of Gwynedd descended from the dynastic family which had ruled for nearly 400 years; when he died without any sons
in 816, Merfyn Frych claimed the crown by right of his mother Esyllt, only daughter of Cynan. About a century and a half later,
Owain ap Hywel Dda had drawn up the group of pedigrees now found in Harleian Ms 3859. The main purpose of doing this,
we would suggest, was to demonstrate Owain's legitimate claim to the kingdom of Deheubarth in Wales. As the great-great-grandson
of Merfyn Frych, Owain traced his paternal ancestry back through Esyllt to Cunedda of the fifth century through Maelgwn Gwynedd,
the famous king we first meet in the Gildas work The Ruin of Britain. 
Born c. 480 to Cadwallon Lawhir ap
Einion Yrth ap Cunedda, Maelgwn was succeeded by his son Rhun Hir, and Rhun by his son Beli. The king of Gwynedd who followed
Rhun was Iago ap Beli; his obit is recorded as 613 in Annales Cambriae. But was Iago's father Beli the same
Beli who was a son of Rhun? The chronology of the family says no; Iago ap Beli and Beli ap Rhun would appear to have
been members of the same generation, both born in the period 540/545. A chart which lists the men in the order cited in Harleian
Ms 3859 will demonstrate this point:
415 Einion Yrth
450 Cadwallon Lawhir
480 Maelgwn Gwynedd
505 Rhun Hir
600 Cadwallon (obit 634)
630 Cadwaladr (obit 682)
665 Idwal Ywrch (obit 712)
Rhodri Molwynog (obit 754)
735 Cynan Tyndaethwy
Most pedigrees of the family
into which estimated birthdates have been inserted date Iago ap Beli to c. 575 and say he was slain in 616 (or 613) at
the Battle of Chester. Although that battle and the obit of Iago are recorded under the same date, we should not
leap to the conclusion that these events were related. Rachael Bromwich notes that the wording in the Annales
Cambriae "Iacob filii Beli dormitatio" suggests that Iago died after having retreated to end his days in a monastery.
Rather than a man of fighting age in 616, Iago had lived out his life expectancy and should be dated much earlier
than is possible for a son of Beli ap Rhun. Also notice in the chart that if we move Iago's birth forward a generation,
it also pushes all his descendants forward leaving us with a Cadwallon who must, under that construction, have been killed
in battle around age 4. Some have tried to gloss over the chronological problems by assuming very short generational
gaps between the men who followed Maelgwn Gwynedd. Having analyzed literally thousands of pedigrees of Celtic men who
lived prior to the year 1100, we find it wholly unreasonable to believe this family for the space of a half-dozen
generations managed to accomplish a feat not seen elsewhere; fit 5 generations in a 120 year span.
Where then should we look for
the ancestry of Iago? Geoffrey of Monmouth apparently knew that the father of Iago was named Beli ap Einion but,
like much of his flawed work, incorrectly identified this Einion as a second son of Maelgwn Gwynedd.
This construction would mean each son of Maelgwn had a son named Beli; while that would be entirely possible, it would do
nothing for our chronological problem. It would not change the number of generations in the pedigree but Geoffrey's introduction
of Einion as the grandfather of Iago should lead us to a solution. Molly Miller called attention to the problem in these words:
"that Rhun was not the ancestor of the subsequent kings of Gwynedd is made almost certain by the chronology and demography,
and such fiction can be readily explained in the interests of the Second Dynasty claiming direct descent from the right line
of Maelgwn". By the "second dynasty", she means the family of Merfyn Frych and specifically Owain ap Hywel Dda who
cast the Harleian pedigrees in the tenth century. She suggests the Einion in "Iago ap Beli ap Einion" was the actual
ancestor and that he was a cousin of Maelgwn. This was probably the King Einion of Lleyn who is cited as the son of Owain
Dantgwyn ap Einion Yrth ap Cunedda.
It was another line of
Owain Dantgwyn, descended from his second son Cynglas, who ruled in Rhos and from which came King Caradog (obit
798) and his son, Hywel; the latter battled Cynan Tyndaethwy for control of Anglesey in 813-816. That contest is
the subject of our paper entitled "Governance of Gwynedd, 754-816".
We conclude with the chart which
shows the corrected descent of the first Gwynedd dynasty:
450 Cadwallon Lawhir 445
480 Maelgwn Gwynedd 475
505 Rhun Hir* 510
540 Beli 540
*Rhun is thought
to have been a base son born to a mistress prior to the first marriage of Maelgwn and probably prior to his brief life as
 De Excidio Brittonum was written c. 540 and denounced for extreme wickedness
five kings then living, including Maelgwn.
 Trioedd Ynys Prydien, 1961, Cardiff, pp 411
 Annales Cambriae cites the death of Cadwallon in the battle of Cantscaul
in 631, a date others emend to 634. He could scarcely have been born a generation later than our c. 600 estimate.
 Refer to our paper "Generational Gaps and the Welsh Laws" for a discussion
of the length of generational gaps among Celtic men of the era.
 History of the Kings of Britain, Book xii, part 6 from the Sebastian Evans
translation in 1903. Geoffrey wrote his fanciful 'history' c. 1136 and while elements of actual history
underlie the work, much of his accounts read more like a novel.
 The Saints of Gwynedd, 1979, Woodbridge, pp 110
 Bonedd y Saint, 9 from P.C. Bartrum "Early Welsh Genealogical Tracts", 1966,
 Harleian Ms 3959, 3