Celtic Britons

The Britons (reconstructed P-Celtic *Pritanī, Latin: Britanni, Welsh: Brythoniaid), also known as Celtic Britons or ancient Britons, were the Celtic people who inhabited Great Britain from at least the British Iron Age until the High Middle Ages, at which point they diverged into the Welsh, Cornish, and Bretons (among others). They spoke Common Brittonic, the ancestor of the modern Brittonic languages.

The oldest written evidence for the Britons is from Greco-Roman writers in the Iron Age. The earliest known mention is by Pytheas (c. 320 BC), who refers to the Pretanoi as being Keltoi (Celts).