Isca Dumnoniorum settlement there (modern Caerleon) to be distinguished as "Isca Augusta", while the Devonian Isca was called "Isca Dumnoniorum": Usk of the Dumnonians. Exeter began as settlements on a dry ridge ending in a spur overlooking a navigable river teeming with fish, with fertile land nearby. Although there have been no major prehistoric finds, these advantages suggest the site was occupied early. Coins had been discovered from the Hellenistic kingdoms, suggesting the existence of a settlement trading with the Mediterranean as early as . This is disputed however by Prof T P Wiseman who alleges the hoard was not genuine. Following
Dumnonii site of the former "principia" and by the late 2nd century the "civitas" walls had been completed. They were 3 metres thick and 6 metres high and enclosed exactly the same area as the earlier fortress. However, by the late 4th century the "civitas" was in decline. As well as Isca Dumnoniorum, Ptolemy's 2nd century "Geography" names three other towns: The Ravenna Cosmography includes the last two names (in slightly different forms, as "Tamaris" and "Uxelis"), and adds several more names which may be settlements in the territory. These include: Other Romano-British sites in Dumnonia include: New settlements continued to