The writings of the early chroniclers, though singularly faithful on the whole, cannot always be implicitly trusted, and it is not often that the facts they record can be authenticated by contemporary documentation, and emphasises in particular the lack of reliability of Heraldic Pedigrees...drawn up from the first with palpable inaccuracies and without any regard for dates.
Some of the areas of difficulty which he highlights are discussed below in the present document.
[The Gwentian Chronicle records that the mother of "Mervyn the Freckled" was "Nest daughter of Cadell of Derrnllwg, son of Brochwel Ysgithrog", after recording that "[the] daughter [of Cynan Tindaethwy king of all Wales] who was his heir married a chieftain of the name of Mervyn the Freckled".
Indeed, it is possible that both Ethyll and Nest were not historical figures at all but were invented to legitimise claims to Gwynedd and Powys, respectively, in the eyes of successor generations of kings and their supporters.] Merfyn & his wife had [two] children: a).
It is impossible to judge which version is preferable.The so-called "Gwentian Chronicle" represents another version of the Chronicle of the Princes/Brut y Tywysogion, allegedly arranged by Caradoc of Llancarvan, with major differences in the text and particular emphasis on southern Wales.However, there is some difficulty associated with the Gwentian Chronicle.The Annales Cambri, said to have been compiled originally in 954, represents the oldest register of events in Wales.The version of the 12th century "Brut y Tywysogion" (Chronicle of the Princes of Wales), published with English translation in the Rolls Series in 1860 by John Williams, was incorporated into the Red Book of Hergest, a manuscript compilation of numerous 6th to 15th century literary works written in the Welsh language.While the surviving sources are consistent regarding the parentage of Ethyll, they are contradictory regarding the identity of her husband.The mid-10th century Harleian Manuscript genealogy names the ancestors of Rhodri "Mawr/the Great": "Rotri map Mermin map Etthil merch Cinnan".Bede records that "rex Brettonum Ceadualla" killed "Osricum" [King of Deira] in , and ruled "provinci Nordanhymbrorum" for a year before also killing "Eanfridum" [King of Bernicia] who had visited Cadwallon to sue for peace.Bede records that "Osualdi", after the death of "fratris [eius] Eanfridi", defeated and killed "Bretonnici regis tyrannidem" (referring to "rex Brettonum Ceadualla") at "Denisesburgna, id est riuus Denisi" --- of Mercia, daughter of [PYBBA of Mercia --- & his wife ---].Dating of early medieval Welsh history is a particular problem as the three main sources referred to above rarely coincide in the dates which they attribute to the events recorded. [The Gwentian Chronicle records that "Gwgan son of Morydd son of Llywarch Llwyd, king of Ceredigion was drowned in crossing the river Llychwr in Gower, to drive the black pagans out of that country" in 870.Bede records that "Caedualla rex Brettonum", helped by "Pendade region genere Merciorum", rebelled against Eadwine King of Northumbria who was killed in battle "IV Id Oct" in 633 at "Haethfelth", adding that the rebels continued to govern the country with varying success for 22 years.