> It is similar in Polish ('country' vs 'edge'/'border'/'region' in Russian) and probably other Slavonic languages.

South Slavs have multiple historical examples of Krajina(s) and they all represented bordering area, edge, (military) frontier. In a broad sense kraj/krai means area, land, place. But krajina(s) were always bordering areas.

https://en.wikipedia.org/wiki/Krajina

There's also Polish example of Krajna, the bordering region between Greater Poland and Pomerania.

https://en.wikipedia.org/wiki/Krajna

Of course, linguistics can and do get politicized so...