Gwerthrynion, often anglicized as Gwernyfed, is an area in Powys, a historic county in central Wales.
A region of Britain named after King Vortigern.
Vortigern fled there after the Saxons took over much of the eastern part of Britain. After Vortigern’s death, Gwerthrynion fell to Vortigern’s son, Pascentius.
Gwerthrynion | 0 to the 9th century AD
Roman Period | 1st – 5th centuries
During the Roman occupation of Britain, which lasted from the first to the early fifth century, Wales was part of the Roman province of Britannia. Roman influence is reflected in various archaeological remains, such as roads, fortifications, and villas.
Post-Roman/Early Medieval Period | 5th – 9th centuries
With the decline and withdrawal of Roman authority in the early fifth century, Wales entered a period often referred to as the Sub-Roman or post-Roman period. Native Britons, influenced by Romanized culture, continued to inhabit Wales. The fifth to seventh centuries witnessed increased migration and invasions, with Irish, Anglo-Saxons, and other groups interacting with the native Britons.
The emergence of early Welsh kingdoms began, with regional rulers establishing territories. The political landscape was characterized by fragmentation and localism.
Anglo-Saxon and Viking Periods
The eighth and ninth centuries saw further interactions with Anglo-Saxons from England, and occasional Viking raids along the coastlines. Wales, including regions like Gwerthrynion, would have been part of the complex relationships between native Britons, Anglo-Saxons, and other groups.
Source
Historia Brittonum | Probably Nennius, early 9th century