I am currently reading The Steel Bonnets by George MacDonald Fraser, which is a history of the border reivers- the violent and wild people who lived on the frontier of England & Scotland in the 16th century. The border culture is interesting both in itself and due to the impact it has had on the wider world. Both the Ulster Plantation and the slightly misnamed "Scotch-Irish" settlers of the USA's Appalachian backcountry derive mostly from the borderers.
I have not finished the book yet so will not attempt a review but one thing that did strike me was how many of the clans on the Scottish side of the border bear surnames which now crop up in the Scottish rugby team over the decades- Armstrongs, Beatties, Redpaths, Weirs and Irvines etc- reflecting that the region is the heartland of the Scottish game. Similarly a lot of the English surnames appear over and again among English footballers of North Eastern origins- Charltons, Milburns, Hendersons and Robsons among them.
There really is a very strong continuity of population in this country that goes back hundreds of years, with families often having lived in the same area over the course of many hundreds of years.