Terra nullius

Terra nullius (/ˈtɛrə ˈnʌlɪəs/, plural terrae nullius) is a Latin expression meaning "nobody's land". Since the nineteenth century it has occasionally been used in international law as a principle to justify claims that territory may be acquired by a state's occupation of it. There are currently three territories sometimes claimed to be terra nullius: Bir Tawil (a strip of land between Egypt and the Sudan), four pockets of land near the Danube due to the Croatia–Serbia border dispute, and parts of Antarctica, principally Marie Byrd Land.