Then please be more specific since I don't know what you mean.
Discussion
After the Louisiana purchase was made, basically there were 3 ways people laid claim to land. One was outright purchase, which seems retarded considering it was basically unoccupied. The other was a homesteading and squatting. I also think some land was granted to certain vets.
The idea that land can only be acquirrd through purchase is slightly ridiculous, what happens when a new island is created in the ocean? Is it basically a "dibs" systems?
This is after the founding of the country. I'm asking about before. Showing up to a region and basically planting a flag and claiming "this is mine now" is rather ridiculous, isn't it? Still, the world we are currently living in has no real undiscovered or unaccounted for land at this point, no matter how spurious prior claims to such land may have been in the past. Given that, I do not recognize *squatter's rights."
As to your last query, I honestly don't know. That's rather farfetched, isn't it?
Thata not far-fetched, it happened in Iceland in 1960s and refutes your point that all land is currently accounted for. Also, who owns the land on the moon, mars, etc? If your philosophy doesnt work at simple edge cases in the present and future, then you have a lot more work to do to justify it in the past. For example, didn't the Indians juat show up from asia via alaska and do the exact thing you said was ridiculous?