Dwyfan and Dwyfach, sometimes also called Dwyvan and Dwyvach, in Welsh mythology, were the equivalents of Noah or Deucalion who take their names from small rivers, as told in a flood legend from the Welsh Triads.[1] A great flood was caused by the monster Afanc, who dwelt in Llyn Llion (possibly Bala Lake).[1] All humans were drowned except Dwyfan and Dwyfach, who escaped in a mastless boat. They built an imposing ship (or ark) called Nefyd Naf Neifion, on which they carried two of every living kind.[1] From Dwyfan and Dwyfach all of the island of Prydain (Britain) was repeopled.[1] Dwyfach appears to take her name from the small Dwyfach (Welsh: little Dwy) River of Gwynedd (until 2018, Caernarvonshire) that flows into Cardigan Bay; Dwyfan would then derive from the river it enters, the Dwyfawr or Dwyfor (Welsh: great Dwy).[1]
Source: Dwyfan and Dwyfach – Wikipedia
Tim B.
“Hu Gadarn is described by Morganwg in his triads as being the earliest inhabitant of Britain having travelled from the “Summerland, called Deffrobani, where Constantinople now stands” in 1788 BC.[13] He is credited as having founded the first civilisation in Britain and introduced agriculture. Morganwg’s Barddas (1862, p. 348) further states that this king is descended from Hu, but that, after a huge flood (see Afanc), only two people, Dwyfan and Dwyfach, survived from whom the later inhabitants of Britain descended. The Welsh clergyman Edward Davies included this myth in his Celtic Researches on the Origin, Traditions and Languages of the Ancient Britons (1804):
“`First, the bursting of the lake of waters, and the overwhelming of the face of all lands, so that all mankind drowned, excepting Dwyvan and Dwyvach, who escaped in a naked vessel and from then the Island of Britain was re-peopled.“`
Several 19th-century Christian authors–for example, Henry Hoyle Howorth[14]–interpreted this myth to be evidence for the Biblical flood of Noah, yet in Morganwg’s chronology Dwyfan and Dwyfach are dated to the 18th or 17th century BC, which does not fit the Biblical estimate for the Noachian deluge.[15] “
Tim B.
quote above:
https://en.wikipedia.org/wiki/List_of_legendary_kings_of_Britain#Kings_derived_from_Geoffrey_of_Monmouth