How exactly caravans work?
The easy thing is that it builds road.
But I also heard that it gives some food bonus. The questions I have how exactly does it work. Is it better to build caravan between my two cities or between my city and AI? Does it matter if one of the cities produces food? Does it matter which of the cities produces food (the one who build caravan, or the one which received caravan). Are there any other bonuses, non-food and road related? Like relationship bonus if you trade with AI?