Don't know David
Will have to see if someone with better knowledge can sort this out. There is a book called "The Drove Roads of Scotland" but I have not seen a copy.
Scotland and England were not always at war. But in recnt memory there was always an amount of tension.
I remember that the Scots Banks had the right to issue their own notes which were legal tender throughout the UK. I remember as a child my mother coming back to our car when travelling through Lancashire after a shop had refused to accept Scottish Banknotes. She was fuming and insulted. I also rememeber English Schoolchildren chanting "Scotland's burning ..." in a malicious way.
In the "less civilised" times of antiquity even different regions in the same country were "foreign" and traders would probably be armed to protect themselves however the prospect of the profits of commerce would push them outside their own territory to fairs and markets where a truce existed. The same problems would probably mean that they would not venture too far accross regional borders.
The raids of the borderers upon one another would make crossing that region (and returning) a hazardous exercise.
The connection I am postulating is many centuries earlier before the national identities were fixed. The cattle (or sheep) would pass through many hands as they made their way south.
This is all conjecture and I would appreciate comment from anyone better informed.