https://en.wikipedia.org/wiki/Roman_Britain
Roman Britain (Latin: Britannia[1] or, later, Britanniae, “the Britains”) was the area of the island of Great Britain that was governed by the Roman Empire, from 43 to 410 AD.[2]:129–131[3] It comprised almost the whole of England and Wales and, for a short period, southern Scotland.
What did you think Harian’s Wall was about? It kept out the Scottish celts.