The idea that Faerun or dnd as a whole doesent know borders is outright false. Just as the notion that during the middle ages we dident have borders. Are you serious? Ofcourse we had borders. Why does everyone believe that the people in the middle ages were uncultured swines who had no form of common sense, were all illiterate and dident wash.
Maybe they werent as accurate as maps today are, but the notion that they dident have any at all is laughably false.
I never said that. Borders are no a sign of enculturation either. What I meant is that border legality is an invented concept that has no bearing on reality unless you start enforcing borders with milltary force, which medieval states never committed enough resources to. You had realms with claims but no state back then was so centralised that it could enforce something like modern day borders or even Roman limes imperii. In the middle ages territory was controlled indirectly through an interdependent relationship between the lord and his vassals. It never came down to rigid lines on a map because nobody was capable of enforcing their borders so strongly.
If you want an example, here is a map of the Netherlands in 1300;
See all those enclaves and exclaves? That is because there is a difference between de jure lands and de facto lands.
Anyway, enough history lessons. None of this really matters in the setting of BGIII beyond the point that it makes Kagha's plotline look silly.