Get some Open Borders already, it does no harm unless that person is someone's worst enemy. Even then, friends are not a bad thing. The Khan and Napoleon are the only two other jewish nations, befriend them. Bribing Napoleon into war with someone else after opening borders should be worth it, it will keep him busy. That would certainly be expensive and risks one AI defeating another and becoming a superpower, but buying time is worth it. If you see either Napoleon or his victim (this would require you opening borders with said victim, so it's unlikely) going down, quickly build some troops, join the war and grab at least some of the cities. A long stalemate in an AI war, like the Portugal vs Mongolia in my game is favorable as well, it utterly ruins the involved civs tech positions.