Yr Hen Ogledd, or in English the Old North, is the historical region that was inhabited by the Brittonic people of sub-Roman Britain in the Early Middle Ages, now Northern England and the southern Scottish Lowlands, alongside the Celtic Kingdom of Elmet. Its population spoke a variety of the Brittonic language known as Cumbric which is closely related to, if not a dialect of Old Welsh. The people of Wales and the Hen Ogledd considered themselves to be one people, and both were referred to as Cymry ('fellow-countrymen') from the Brittonic word combrogi. The Hen Ogledd was distinct from the parts of Great Britain inhabited by the Picts, Anglo-Saxons, and Scoti.

The Britons, also known as Celtic Britons or Ancient Britons, were an indigenous 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. They spoke Common Brittonic, the ancestor of the modern Brittonic languages.