I know this is a very peripheral point but habitable "unclaimed" land has not really existed through most of human history. At best there might be the occasion

I know this is a very peripheral point but habitable "unclaimed" land has not really existed through most of human history. At best there might be the occasional power vacuum. Just existing is a political act and the unit of human survival is tribe-sized or larger. Land described as "unclaimed" is typically a convenient fiction used to support sovereignty transfer.