[remarkEon]

Part of the reason this thread and this topic is so fraught is there are many people, like you, who are willingly and confidently lying about history. Strict borders have existed since ancient times. There are physical markers of them all over Europe that are more than 1000 years old. You can see other borders from space. This idea that only in the 20th century did this idea emerge is so wrong that it’s got the history completely and totally inverted. Why make stuff up like this?

[beepbooptheory]

How did they enforce strict borders in the distant past then?

[pfannkuchen]

“Look there’s an X, what is he doing here, get him!”

[nl]

To add to this, there are numerous well known examples.

For example the Bible defined borders of "The Land of Israel" which are still fought over today: https://www.biblica.com/bible/?osis=niv:Ezekiel%2047:13%E2%8...

The "Eternal Treaty" between the Hittites and Egyptians defined spheres of influence and position of various cities

The Peace of Antalcidas defined the border between Greek and Persian influence and assigned various cities to different powers: https://en.wikipedia.org/wiki/Peace_of_Antalcidas#Effects

One of the biggest drivers of strict borders was tax collection: they defined who could collect tax from which subjects. This was a common source of conflict and so anywhere feudalism was practiced strong border definitions were strongly enforced.

It's possible the grandparent is talking more about the idea of limiting travel across those borders. That is a more defensible position but even then it was more about the the costs of enforcement.

Trade routes had very strong border enforcement because the borders were places taxes were collected for example, and there were limits on who could travel various routes.

For example Venice, Genoa and the Ottoman Empire jealously protected European end of trade routes linking to the spice road.