Dumnonia until they submitted to the See of Canterbury in the mid-9th century. Parish organisation was a later development of fully Normanised times. Around AD 55, the Romans established a legionary fortress at "Isca Dumnoniorum", modern Exeter, but west of Exeter the area remained largely un-Romanized. Most of Dumnonia is notable for its lack of a villa system, though there were substantial numbers south of Bath and around Ilchester, and for its many settlements that have survived from the Romano-British period. As in other Brythonic areas, Iron Age hillforts, such as Hembury and Cadbury Castle, were refortified in post-Roman times for
England–Wales border Insular Celtic languages, and were regarded as Britons. The clear geographical divide between the mountainous western areas of southern Britain and the generally lower-lying areas to the east was reflected in the pattern of Roman occupation. The main Roman military bases for the control of what became Wales were beyond the mountains, at "Deva" (Chester), "Viroconium" (Wroxeter, near Shrewsbury), and "Isca Augusta" (Caerleon, near Newport), all located close to the later national border. When the Roman garrison left around 410, the various parts of Britain were left to govern and defend themselves. The western area, later Wales, had become largely