Pengwern was a Brythonic settlement of sub-Roman Britain situated in what is now the English county of Shropshire, adjoining the modern Welsh border. It is not clear whether it was a kingdom or merely a Royal residence.
Nothing is known about the foundation of the settlement, although it is traditionally thought to have been part of the Welsh kingdom of Powys at some point. Pengwern and Powys are perhaps divisions of the ancient pre-Roman Cornovii tribe whose civitas capital or administrative centre was Viroconium Cornoviorum (now Wroxeter). David Nash Ford suggests that the rulers originated in Dogfeiling, around Rhuthin.
The exploits of Cynddylan ap Cyndrwyn Fawr, the ruler of Pengwern, are recorded in the Old Welsh tragic poems, Marwnad Cynddylan and the Canu Heledd (a cycle of poems named after Cynddylan's sister), dating from the 7th century.
A number of places still identifiable in the Shropshire landscape today are mentioned alongside Pengwern in this poetry. The exact location of Llys Pengwern - the Royal Court of Pengwern - is not known, but strong local tradition, first mentioned in the 12th century, claims that it was thought to be the original foundation of modern Shrewsbury (although Welsh people today call this Amwythig). A more recent suggestion is the Berth, a dramatic hillfort at Baschurch. Wroxeter, the former Roman town of Viroconium Cornoviorum lies in proximity to these places. Nennius says it was known as Caer Guricon and archaeological evidence suggests that this town continued in use after the Roman withdrawal and was only finally abandoned in about 520 when it had become indefensible as the last vestiges of Romano-British central government broke down. It is often suggested as a capital for the Pengwern region.
King Cynddylan apparently joined forces with King Penda of Mercia to protect his realm, and together they fought against the increasingly powerful Anglian Kingdom of Northumbria at the Battle of Maes Cogwy (Oswestry) in 642. It was here that their mutual enemy, King Oswald was slain. This seems to have bought a period of peace to Pengwern until Penda's death when a Northumbrian raiding party led by Oswald's brother Oswiu of Northumbria overran Cynddylan's palace at Llys Pengwern in a surprise attack. Caught completely off guard and without defence the royal family, including the king, were slaughtered. Princess Heledd was the only survivor and lived her life in Powys. After this the region seems to have been absorbed into both Mercia and Powys. The Western portion of Pengwern became what was known as Paradys Powys or the "Paradise of Powys" which remained in Welsh hands until the reign of Offa of Mercia and the construction of his dyke.
In Shrewsbury there is the Pengwern Boat Club on the banks of the River Severn, opposite The Quarry park, as well as other shops and businesess that use the name.