I suppose it depends a bit on what type of ownership. Lots of land has nominally passed between nations without affecting the people using there, or gone from c

I suppose it depends a bit on what type of ownership. Lots of land has nominally passed between nations without affecting the people using there, or gone from communal to private without leaving the families of (some of) the residents. In collective/national terms, Iceland and most of Tuvalu could count - genuinely uninhabited territory settled by ancestors of the people who live there now. (Tuvalu was a British Crown colony, but on some of the smaller islands that doesn't seem to have actually changed much.) As far as "the same group continuously owned this acreage", I was sort of stunned to learn that parts of the Fort Apache Reservation probably qualify. The White Mountain Apache entered the region perhaps 100 years after the Mogollon population completely abandoned it to drought, and have apparently held it for 500+ years since without ever being removed by war or the US government. Even legally, it appears to have been held by the tribe collectively (and acknowledged as such by the USG) throughout history.