Bug:
As the French it is possible to use diplomacy and win by domination in the first turn. The other civs will trade cities with you for a mutual protection pact. Hell, some of them will tade ALL their cities (except capitol of course). This means for absolutely no cost you can control 40% and more of everything in one turn!!!

This is a well documented issue. I'm fairly certain Firaxis knows about it already. Just don't trade during the first turn. IIRC, this occurs due to the fact that as France you play first so the AI doesn't have time to evaluate his respective position so he gives in to anything...