Get yourself a pencil and a piece of paper. You're going to draw what I describe.
- In the center, draw a small circle--trace a US quarter-dollar coin if you like--about 1 inch (or its Metric equivalent) across in diameter. Inside this, write "Hearth".
- Draw a second circle, about 2 inches across in diameter using the center of the first circle as its center. In the space between the first circle and the outer edge of this second circle, write "Bawn".
- Outside the second circle, write "Here Be Monsters".
- Across the outer edge of the second circle, write "Outer Border"; across the first circle's edge, write "Inner Border".
Only with the massive changes wrought by industrialization are we now able to entertain, and for some time sustain, deviations from this norm; the current weakened traditional division can only persist so long as the technology does, and without the old ways will rush in like the water after a broken dam. Even so, those who adhere to this pattern thrive and prosper in a resilient manner across the generations while those that fall away find that their end is like that of a drug addict: broken, ruined, and wasted due to the consequences of their folly taking their toll.
This paradigm is fractal. You can see it in the form of an individual household or homestead. You can scale it up infinitely; this works for the border fort and its surrounding farmlands, the nascent country and the empire it broke away from, and even interstellar--yes, even cosmic--scale organizations like the Galactic Empire and the Time Lords of Gallifrey. You can easily discern how well it will go by focusing upon how well the nation(s) within it appreciate and adhere to its premises; weakening and degenerate forms allow violations of the premises for one false reason or another, while healthy and prospering ones strictly adhere to it and exterminate threats to it.
Be it a tool for real-world socio-political analysis, or as a tool for world-building when creating fictional milieu for literature or gaming purposes, you will never fail to go wrong by remembering that we are a species that works around creating defensible spaces for our young and infirm (and those who care for them), surrounding them with the spaces we use to cultivate our economic resources, and then defining what the line--the perimeter--between Our Land and Monster Land is by patrolling it with our fighting-ready men and boys. (Because, at the last, losing those to enemy attacks is recoverable if infrequent enough; men remain the disposible, expendable, and fungible sex in Mankind.)