The Britons fled in a body towards Strathclyde, leaving the country to be settled by the advancing English.
In the same way we might speak of the people of Strathclyde or of Northumbria in early English history.
This was no doubt a traditional idea in those families that migrated to Wales in post-Roman times from Strathclyde.
The southern part of the kingdom of Strathclyde had for some time been under the English kings.
The northern Kymry of Strathclyde were no longer formidable, and they grew less formidable as years passed on.
Early in the 7th century the Brythons of Strathclyde were similarly isolated by the battle of Chester .
His "Cumbrians" are identified with the "Welsh" of Strathclyde.
Originally it was called Alcluyd, and it was the chief town of Cumbria or Strathclyde.