Four groups of frontier peoples drew more or less advantage from the demobilization law--the people of the Toba, the Tibetans, and the Hsien-pi in the north, and the nineteen tribes of the Hsiung-nu within the frontiers of the empire. In the course of time all sorts of complicated relations developed among those ascending peoples as well as between them and the Chinese. The Toba (T'o-pa) formed a small group in the north of the present province of Shansi, north of the city of Tat'ungfu, and they were about to develop their small state. They were primarily of Turkish origin, but had absorbed many tribes of the older Hsiung-nu and the Hsien-pi. In considering the ethnical relationships of all these northern peoples we must rid ourselves of our present-day notions of national unity. Among the Toba there were many Turkish tribes, but also Mongols, and probably a Tungus tribe, as well as perhaps others whom we cannot yet analyse. These tribes may even have spoken different languages, much as later not only Mongol but also Turkish was spoken in the Mongol empire. The political units they formed were tribal unions, not national states. Such a union or federation can be conceived of, structurally, as a cone. At the top point of the cone there was the person of the ruler of the federation. He was a member of the leading family or clan of the leading tribe (the two top layers of the cone). If we speak of the Toba as of Turkish stock, we mean that according to our present knowledge, this leading tribe (_a_) spoke a language belonging to the Turkish language family and (_b_) exhibited a pattern of culture which belonged to the type called above in Chapter One as "North-western Culture". The next layer of the cone represented the "inner circle of tribes", i.e. such tribes as had joined with the leading tribe at an early moment. The leading family of the leading tribe often took their wives from the leading families of the "inner tribes", and these leaders served as advisors and councillors to the leader of the federation. The next lower layer consisted of the "outer tribes", i.e. tribes which had joined the federation only later, often under strong pressure; their number was always much larger than the number of the "inner tribes", but their political influence was much weaker. Every layer below that of the "outer tribes" was regarded as inferior and more or less "unfree". There was many a tribe which, as a tribe, had to serve a free tribe; and there were others who, as tribes, had to serve the whole federation. In addition, there were individuals who had quit or had been forced to quit their tribe or their home and had joined the federation leader as his personal "bondsmen"; further, there were individual slaves and, finally, there were the large masses of agriculturists who had been conquered by the federation. When such a federation was dissolved, by defeat or inner dissent, individual tribes or groups of tribes could join a new