Dumnonii the origin of the interpretation of Dumnonii as "deep valley dwellers" from his understanding of the Welsh of his time. John Rhys later theorized that the tribal name was derived from the name of a goddess, "Domnu", probably meaning "the goddess of the deep". The proto-Celtic root *dubno- or *dumno- meaning "the deep" or "the earth" (or alternatively meaning "dark" or "gloomy") appears in personal names such as Dumnorix and Dubnovellaunus. Another group with a similar name but with no known links were the Fir Domnann of Connacht. The Roman name of the town of Exeter, "Isca Dumnoniorum" ("Isca of
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