The British territory of Pengwern was conquered by Oswiu of Northumbria in 656, while he was overlord of the Mercians. Western Pengwern was then occupied by Anglian groups. One group based itself at the old Roman town of Magnae or (Old Welsh) Cair Magon, modern Kenchester near Hereford.
The sub-kingdom of the Western Hecani existed in the late 7th and early 8th centuries, of which three rulers are known: Merewalh, Mildfrith, and Merchelm. By the later 8th century, the region would seem to have been reincorporated into Mercia, perhaps as Westerna, becoming known as the Magonsæte by the 9th century.
- The Origins and Growth of Hereford, Archaeology Data Service. Retrieved 25 September 2006.