CAER DATHAL AND ITS ANCIENT RULER

Craig-Y-Dinas on the Afon Llyfni in Arfon, Gwynedd

Craig-Y-Dinas With Adjacent Eithinog-Wen

Place-names can be amazing.  Sometimes, if we get lucky, they can point the way to really significant discoveries. 

My readers know by now that for quite some time I've been trying to identify the ancient Caer Dathal, a very important fort in Arfon, Gwynedd.  While I've come up with some clever results, none of them for convincing.  Some may even have been rather silly.

So what I did was go back to beginning of my research.  Professor Hywel Wen Owen had once told me that Melville Richards, the famed Welsh place-name scholar, guessed that Dathal was a Cymracization of the Irish name Tuathal.  This has been discussed by other scholars since, including Patrick Sims-Williams in his Irish Influence on Medieval Welsh Literature.  

Now, I knew that Irish tradition claimed that the famous Tuathal Techtmar (see https://en.wikipedia.org/wiki/T%C3%BAathal_Techtmar) had lived for many years in Britain, and that his mother was the daughter of a British king.  I hadn't paid much attention to his mother - and to my peril.  

Her name is Eithne Imgel or Eithne 'the [very] white.'.  Her epithet Imgel, according to the eDIL, is comprised of the intensive prefex imm- plus gel, white, fair, bright, shining. Now. while Eithne is from Irish etne, 'kernal', it could easily been wrongly substituted for Welsh eithin, 'furze, gorze' (cf. Irish aittenn).  Hard by the Craig-Y-Dinas fort on the Afon Llyfni (one of the prime candidates for Dathal simply because of its ideal location in relationship to the other MABINOGION place-names linked to that fort) is a place called Eithinog-Wen.  Eithinog means 'full of gorse', while Wen is from Welsh gwen, 'white, shining, bright.'

MABINOGION Sites Near Caer Dathal/Craig-Y-Dinas

In other words, by telling us that Tuathal's British mother was named Eithne Imgel, the Irish tradition is letting us know in no uncertain terms that Tuathal's fort was Craig-Y-Dinas at Eithinog-Wen in Arfon.

The geography fits the story.  In MATH SON OF MATHONWY, we are told that "Gwydion went away angry and made for Caer Dathal and spent the night there. The next day he rose and took the boy [Lleu] and went for a walk along the shore between Caer Dathal and Aber Menai."

Immediately after this the two go to Caer Arianrhod, a rocky island off the coast between Craig-Y-Dinas and Dinas Dinlle, a promontory fort, and then they go to Dinas Dinlle itself (the 'Town of the Fort of Lleu').

Also mentioned in the context of these places is the birth of Dylan, whose name is preserved immediately west of Craig-Y-Dinas.

There simply is no other fort in the region that fits the context as well as Craig-Y-Dinas.