There is no land ownership. It is an illusion. It's pretend. It's not something you can find in nature.
Thus, if you're going to play a pretend game, you need a government so that you're "rights" to that land can be protected.
The fact that real property is not something found in nature, means that it really isn't a right. It is something that can only be born from an agreement that is made between all of the inhabitants of a territory. It is an invention of the mind.
Yours, you must admit, is a bizarre view. Rights are natural if they exits in absence of any legislation, that has nothing to do with naturalness of the underlying conduct. Besides, even animals have string territorial instincts, so real property rights apply to a naturally occurring behavior. That is probably too long a tangent.
As I noted in #95, all that is needed to implement property rights is a convention on posting land, or its paper equivalent -- a registry of deeds.