This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book is concerned with the Kachin and Shan population of North-East Burma, but it is also Intended to provide a contribution to anthropological theory. At one level of abstraction people may discuss social structure simply in terms of the principles of organisation that unite the component parts of the system. At this level the form of the structure can be considered quite independently of the cultural content. Every real society is a process in time. The changes that result from this process may usefully be thought of under two heads. Political units in the Kachin Hills Area vary greatly in size and appear to be intrinsically unstable. At one end of the scale one may encounter a village of four households firmly asserting its right to be considered as a fully independent unit.