Welsh Triads

"[1] The texts include references to King Arthur and other semi-historical characters from sub-Roman Britain, mythic figures such as Brân the Blessed, undeniably historical personages such as Alan IV, Duke of Brittany (who is called Alan Fyrgan) and Iron Age characters such as Caswallawn (Cassivellaunus) and Caradoc (Caratacus).

Teir Gormes a doeth y'r Enys Hon, ac nyt aeth vrun dracheuyn: Ỽn o nadunt Kywdaỽt y Corryanyeit, a doethant eman yn oes Caswallawn mab Beli, ac nyt aeth ỽn un onadunt dracheuyn.

Tryded, Gormes y Saesson, a Hors a Hengyst yn benaduryeit arnadunt.One of them (was) the people of the Cor(y)aniaid, who came here in the time of Caswallawn son of Beli: and not one of them went back.

Other important manuscripts include Peniarth 45 (written about 1275), and the pair White Book of Rhydderch (Welsh: Llyfr Gwyn Rhydderch) and Red Book of Hergest (Welsh: Llyfr Coch Hergest), which share a common version clearly different from the version behind the collections in the Peniarth manuscripts.

Some of his triads are similar to those found in the medieval manuscripts, but some are unique to Morganwg, and are widely believed to have been of his own invention.