Devon is a large county in South West England, bordering on Cornwall to the west, Dorset and Somerset to the east. Both parts of the Devon coastline are part of the South West Coast Path. The name given by the Romans to the Celtic people who inhabited the south western peninsula of Britain at the time of the Roman invasion c. 50AD , known as the Dumnonii, thought to mean 'Deep Valley Dwellers'. Devonshire parishes Later the area became a frontier between Brythonic Dumnonia and Anglo-Saxon Wessex.