A lot of physical "property rights" are equally dubious though and probably shouldn't have the reverence people have for them. The reason why land ownership reform (splitting up of big land holdings owned by the wealthy but farmed by the poor) was a big issue in 19th century Britain (and Ireland which was completely part of it then) and still is an issue in the developing world today, is ultimately it is arbitrary that somebody gets to "own" land just because they are descended from aristocrats who conquered it centuries ago.