no man's land
noun
an area between opposing armies, over which no control has been established.
an unowned or unclaimed tract of usually barren land.
an indefinite or ambiguous area where guidelines and authority are not clear: a no man's land between acceptance and rejection.
(in tennis, handball, etc.) the area of a court in which a player is at a tactical disadvantage, as the area of a tennis court about midway between the net and the base line.
Origin of no man's land
Middle English word dating back to 1300–50