This is a common scenario for me: 1. Research Industrialization 2. There is no coal anywhere near my territory 3. Scour the globe for some coal 4. Find a few CS with coal within their borders 5. Play guessing game as to if/when the CS actually has access to the coal, so you can get it by allying them Sometimes it's obvious the CS hasn't hooked up the coal because there's a lumber mill on that tile, but sometimes there's a mine already on the tile. I know I'm the tech leader and other civs/CS can't see coal yet, but my question is: how do you know when they actually do get access to the coal, making it available to you via allying them? I know CS have an internal tech tree, but I have no way to tell if they research Industrialization.