Witmonger

Is there truly no way to break a treaty? Three hours into my first game and both my cities are locked away from the rest of the map by an "ally's" town that's cutting me off from everyone else. And even though I now have an alliance with them, I can't move my units through their town? Really??? I've never played a single RPG/strategy game where having an alliance with another faction doesn't let you move troops through their cities. So to reiterate in the simplest terms, I can't move