Poul and Karen Anderson's Gratillonius was stationed at Hadrian's Wall before he became the last King of Ys. SM Stirling's post-Change characters refer to the disputed territory between England and Scotland where, for a while, no one's law was enforced. I grew up in Border country and now live just south of it. When I revisited the English Lake District, the guy in a gift shop had a Scottish accent but, when I commented, "You're not local!," he replied, "All this belonged to Scotland years ago!" Good answer.
Manse Everard of the Time Patrol, talking to Mongols invading North America, claims to:
"'...belong to the border guardians.'" (Time Patrol, p. 138)
It is good to know that our humble border has a temporal equivalent. Now that Britain is leaving the EU, the Scottish First Minister is requesting a second Independence referendum. The chaos continues.