Although of course, it's purely the limits of the engine, and awkward situation happened. I tried a game as the Turks and conquered "Europe." I think maybe a nigh indestructible defensive unit that can't be moved, like I had in my cities on the edge of the map for my Mexican War of Independence scenario back in MGE for the port cities of Spain, Britain, and France, might fix this kind of problem. In my own old Vietnam scenario, it was much easier, because the North Vietnamese and Chinese had no units or mechanisms to reach the "Stateside" city on the edge of the map for the US, and likewise for the North Koreans and Chinese to the occupied Japanese cities on the edge of the map for the UN in the Korean War scenario I'm just finishing up. I thought I'd bring this up. It's been an occasional issue in a few scenarios where one or more player are fighting (or colonizing, in a few cases) on the map, but their home territory and main centre of production are effectively "off-map."