I have been playing the game again after a break, and I am running into a couple things that confuse me: 1) I keep finding that AI civs have open borders by default. I just met the Gauls on turn 152, and I can enter their territory on the next turn. Not the first time I have seen this. As best as I can see, other civs cannot enter my territory. So what gives here? 2) I am finding it unpredictable when an alliance will pull me into a war (or when it will pull an ally into a war). This morning, I was friends with Japan and allied with Rome, and Japan declared war on Rome. I was not pulled in. Why? And does this mean that if Japan declared war on me (after the friendship expired), then I would have been on my own? To be clear, this was an economic, not a military alliance, but I believe the Civilopedia states that all alliances bring allies into a defensive war.