Thanks for the feedback! The thing is, the Sioux are set to expand like crazy (flavor of 10, I believe). Expansion is the main play style which really suits the AI (and all the AI happiness, etc. bonuses allow them to do it much more proficiently than a human player). If you look at the mini-map of the first image, the Sioux have at least 10 more cities than any other civ. However, the Sioux also don't get any innate happiness or settler production bonuses to boost this. While their abilities are designed around quickly beefing up a newly founded city, how well the AI actually uses this design is questionable, so I feel it's more a combination of a high expansion flavor and the bonuses the AI naturally get than something specifically stemming from the civ. Of course, less American civs highlights the issue as the Sioux have more land to freely settle into. (Including the Shoshone might help as they start near the Sioux while also expanding a lot and naturally claiming bonus tiles. I believe Col Leg's Cree and Blackfoot civs also have YnAEMP starts near the Sioux, which would give them less places to settle uninhibited). IDK, I doubt if a human player could play the civ the same way so easily. In my own tests (using just a random map and standard settings), the end results usually end up more balanced (or at least the Sioux were no more runaway than the other super expansion hungry civs). I might run a test game similar to your setup but give the Sioux YnAEMP coordinates to start in the middle of Europe, and see how much that affects the outcome. It's something I continue to watch, but haven't decided if I'm going to change at the moment.