Cornovii (Cornwall) Dumnoniorum (present day Exeter), it is likely that he only listed Roman places, not purely native sites. Of these, there has been speculation that Voliba might be a place in Cornwall and Tamara is assumed to be on the River Tamar, the border between Cornwall and Devon. Ptolemy's list is supplemented by the problematical Ravenna Cosmography, which lists sixteen names before Isca Dumnoniorum (which is listed as "scadum namorum", showing some of the problems of this source) and which have therefore been assumed to be west of Exeter. Several have been identified as most likely in Devon, leaving "purocoronavis" (the
Celtic language decline in England England begin to be attested from around 670, pre-eminently in Anglo-Saxon charters; they have been intensively surveyed by the English and Scottish Place-Name Societies. Except in Cornwall, the vast majority of place-names in England are easily etymologised as Old English (or Old Norse, due to later Viking influence), demonstrating the dominance of English across post-Roman England. This has traditionally been seen as evidence for a cataclysmic cultural and demographic shift at the end of the Roman period, in which not only the Brittonic and Latin languages, but also Brittonic and Latin place-names, and even Brittonic- and Latin-speakers, were swept away.