A fascinating subject. I’m puzzled why this image talks about ‘the Scots’ as if they were one people. I’d say they were 5, basically 4 quarters centred on Stirling, top left are Scots, top right Picts, bottom right including Edinburgh originally British then Anglo-Saxon, bottom left including Glasgow British Welsh. And bordered to the North and West by Vikings.
I wish I knew where I was from, the only bit I know for certain is on my mother’s side, her Dad was Devon and her Mum the Anglo-Saxon bit of Pembrokeshire, the Pembrokeshire Englishry as it was known.