People move. That might seem to be a rather self-evident statement with which to begin, but it’s the central fact of this book. We are creatures capable of traveling substantial distances at a rapid pace. And it is fair to say that our ability to walk (and run) extraordinarily long distances is one of our defining traits as a species, along with our technological augmentations of that ability. Despite its obviousness, this fact is often obscured from the central narratives of international politics and the development of international law.