For a recent (within the last 100 years) example of Terra Nullius, look at Svalbard and the Svalbard treaty. Any citizen of a signatory to the treaty is entitled to live there. In practice it's kind of hard to do, since there's not much economic activity up there and logistics/transport costs and energy costs makes everything very expensive. But theoretically an Afghan citizen could move to Svalbard freely.

https://en.wikipedia.org/wiki/Svalbard_Treaty

also, no, it does not have any armored polar bears.