Generon, Generth, Genoreu, Guorthegrin, Gwrtheyrnion, Vortigern
Ganarew is a small village situated in the eastern part of Monmouthshire, Wales, near the town of Monmouth.
A castle on Mount Doward in the country of Archenfield in Wales. The castle sat along the River Wye. According to Geoffrey of Monmouth, King Vortigern fled to this castle when pursued by Ambrosius Aurelius and Uther, who had come from Brittany to conquer the land. Vortigern fortified himself, but Ambrosius simply set the castle on fire and burned Vortigern alive.
Nennius calls it Vortigern, a fortress built by Vortigern. Nennius says that it is in North Wales, but he later places it in Dyfed, in South Wales.
Sources
Historia Brittonum | Probably Nennius, early 9th century
The Fairy of the Lake | John Thelwall, 1801
Historia Regum Britanniae | Geoffrey of Monmouth, c. 1138
Roman de Brut | Wace, c. 1155