You're conflating issues here and you know that. Empires expanded and contracted; wars of conquest were normal (good or bad). Agricultural people always saw uncultivated lands as unclaimed lands. This was true in China, Mesopotamia. Rome and the Americas.
We now have a DIFFERENT situation and your conflating them and coming up with a snarky is sign of your not willing to deal with the problems at hand. We have existing countries, with borders, with laws and in which the state compels it's citizens to act in a certain way. Now - what you're saying is that government can pass zoning laws to regulate density but they cannot control who comes into the country? The illogic of your position should be clear.
Now please, by pass the snarky comments, and confront the issue.