Jurisdiction refers to the claim of one or more people calling themselves a sovereign to have the right to make and enforce laws over people, usually in a geographic area.
To prove jurisdiction, one must have evidence of an explicit contract with those over whom one claims to have jurisdiction. A social contract does not meet the elements of a contract, as such it is not evidence of jurisdiction. Being in an area where someone claims to have jurisdiction does not prove jurisdiction either, because just because someone is somewhere that doesn't prove that someone else has any rights over that place.