How guarded were "national" borders in the middle ages?

by sonny1993

Let's say I'm an avid traveler and I want to walk from Toledo to Prague in the year 1300. Modern maps show clear borders between Castille, France, the Holy Roman Empire etc., but would there be anything to mark that? Will I have to identify myself at custom stops and guard posts along the road, or would that only happen if I try to enter a city?

WelfOnTheShelf

There was a similar question last year with answers from sunagainstgold, u/J-Force, and myself:

It's the European middle ages, and I'm traveling from England to Rome or Jerusalem for a pilgrimage. What's border security like, as I cross (presumably) multiple international borders along the way? Do I need a passport or some equivalent?

Edited to add another answer from u/Asinus_Docet:

How do ancient/medieval borders work?