And how is sovereignty established?
1. You occupy a land mass
2. Other countries (your neighbors primarily) agree to recognize you and establish a border.
I had a feeling you'd say that.
The problem is that governments are not literal things, there are only people and their relationships with each other.
Whenever someone abstracts away the flesh-and-blood person to the government or country, they lose sight of the fact that the relationship of government is tantamount to slavery.
"You do as I say because 51% of the voting public put me in charge."
The only legitimate government is one with 100% public support 100% of the time. In other words, none in the history of mankind.
Private property, homesteaded by an individual, is on a much firmer philosophical and ethical basis than a government that claims it derives authority from the masses.