The Dumnoni will be the ancient native Celtic Britons of the southwest tip of the island, presently where Cornwall and Devon are today. This land will be traditionally referred to as the west country.
The native Britons will so refer to themselves in this region as the Dumnoni and their land as Dumnonia. When the Saxon invaders begin their conquest of the eastern and southern parts of the island in about 400–500 CE, they will drive out the native Britons there in the flat farmlands that the Saxons will covet, and drive them to the highlands of the west and southwest (not much good for farming anyway).
The Saxons will call the highlands in the west, whose people refer to themselves as Cymri, Wales, which is Saxon for stranger. Similarly, the Saxons will call the head lands of the southwest Cornwall, which means strangers of the head lands. The wal in Cornwall will be the same root as the wal in Wales.
The famous Cornish prince, or battle–chief, Arthur, a Briton, will fight the Saxons and bring about a temporary peace of over twenty years before the inevitable conquest of the lands by the Anglos, Saxons, and Jutes—the European that will be known at the Denmark and Netherlands area. These conquerors will become what we call the English, as opposed to the Britons. Much nonsense will be written about the gallant, canny, and noble Arthur, but in one of the greatest ironies of history, naive folk after his passing will refer to him as King Arthur of England when, in fact, he opposed bitterly those people we call the English. Arthur will be a Briton.