The most famous monarch was perhaps Cynlas Goch, the son of Owain Ddantgwyn, who lived in the early 6th century and was denounced by the monk, Gildas. He wrote (in Latin) that Cynlas was the “guider of the chariot which is the receptacle of the bear“. The latter may refer to a “Fort of the Bear”, possibly Dinerth, the name of a hillfort on Bryn Euryn in Llandrillo-yn-Rhos. The road that runs below the western side of the hill is still called Dinerth Road and Dinarth Hall is nearby.