Gwrtheyrnion

Gwrtheyrnion, or Gwerthrynion, was a possible early medieval minor kingdom and attested later medieval commote of mid-Wales, supposedly named after its traditional founder, Gwrtheyrn (the Welsh form of Vortigern) who, according to tradition, was High King of the British Celts c.425 - c.455.

The territory is small consisting of four parishes[1] presently within the district of Radnorshire in the modern county of Powys. The historical centre of Gwrtheyrnion was Rhayader from which it is thought the traditional county of Radnorshire was named. Gwrtheyrnion was often united with the neighbouring realm of Builth and came to be ruled by members of the Deheubarth princely house prior to annexation by Marcher Lordships in the early middle ages.

Gwrtheyrnion is first mentioned in the Historia Britonum the 9th Century work attributed to the monk Nennius, viz;

Saint Germanus admonished Vortigern to turn to the true God, and abstain from all unlawful intercourse with his daughter; but the unhappy wretch fled for refuge to the province Guorthegirnaim, so called from his own name, where he concealed himself with his wives: but St. Germanus followed him with all the British clergy, and upon a rock prayed for his sins during forty days and forty nights.