"Earl Efrog held an earldom in the North"
'The Old North'
Creative Commons Attribution Share Alike'The Old North' - Credit: Notuncurious

Efrog is the Welsh name for York.

The ‘North’ may be equated with what is sometimes described as ‘The Old North’ (Yr Hen Ogledd). This is the term given to those parts of northern England and southern Scotland where a Brythonic-based language was spoken in the early medieval period between approximately 500 and 800. Brythonic was the language of the ancient Celtic people of Britain which evolved into four separate languages: Welsh, Breton, Cornish and Cumbric.