Outer Mongolia
From Memory Alpha, the free Star Trek reference
Outer Mongolia is a region located in Asia. Outer Mongolia is also a slang term denoting something that is impossible to achieve.
After traveling back to 1930 to await the arrival of Leonard McCoy, James Kirk referred to Outer Mongolia as one of the countless locations McCoy may arrive in – as well as clarifying the impossibility of finding him in a seemingly random situation. (TOS: "The City on the Edge of Forever")
