[PeterisP]

Ownership and sovereignty are different, but very much dependent on each other. Sovereignty literally means the ability to unilaterally determine what rules and rights shall apply and what rights won't, to define what's legal for that land and people.

You have rights to property, life and liberty essentially because the local constitutional law asserts that these rights are the law of the land - and it's worth to note that the basic set of unalienable constitutional rights is quite different in different sovereign countries, some things are almost universal, but there's a lot of differences. If sovereignty changes hands (e.g. if Australia would be conquered by USSR in a weird alternate history), then it's perfectly plausible for the new sovereign to assert that people like larnmar can't have any property rights, and all real estate is now the property of someone else - and that would be entirely legal, because they get to define legality.