The Tibetans fell apart into two sub-groups, the Ch’iang and the Ti.  Both names appeared repeatedly as political conceptions, but the Tibetans, like all other state-forming groups of peoples, sheltered in their realms countless alien elements.  In the course of the third and second centuries B.C. the group of the Ti, mainly living in the territory of the present Szechwan, had mixed extensively with remains of the Yueeh-chih; the others, the Ch’iang, were northern Tibetans or so-called Tanguts; that is to say, they contained Turkish and Mongol elements.  In A.D. 296 there began a great rising of the Ti, whose leader Ch’i Wan-nien took on the title emperor.  The Ch’iang rose with them, but it was not until later, from 312, that they pursued an independent policy.  The Ti State, however, though it had a second emperor, very soon lost importance, so that we shall be occupied solely with the Ch’iang.

As the tribal structure of Tibetan groups was always weak and as leadership developed among them only in times of war, their states always show a military rather than a tribal structure, and the continuation of these states depended strongly upon the personal qualities of their leaders.  Incidentally, Tibetans fundamentally were sheep-breeders and not horse-breeders and, therefore, they always showed inclination to incorporate infantry into their armies.  Thus, Tibetan states differed strongly from the aristocratically organized “Turkish” states as well as from the tribal, non-aristocratic “Mongol” states of that period.

The Hsien-pi, according to our present knowledge, were under “Mongol” leadership, i.e. we believe that the language of the leading group belonged to the family of Mongolian languages and that their culture belonged to the type described above as “Northern culture”.  They had, in addition, a strong admixture of Hunnic tribes.  Throughout the period during which they played a part in history, they never succeeded in forming any great political unit, in strong contrast to the Huns, who excelled in state formation.  The separate groups of the Hsien-pi pursued a policy of their own; very frequently Hsien-pi fought each other, and they never submitted to a common leadership.  Thus their history is entirely that of small groups.  As early as the Wei period there had been small-scale conflicts with the Hsien-pi tribes, and at times the tribes had some success.  The campaigns of the Hsien-pi against North China now increased, and in the course of them the various tribes formed firmer groupings, among which the Mu-jung tribes played a leading part.  In 281, the year after the demobilization law, this group marched south into China, and occupied the region round Peking.  After fierce fighting, in which the Mu-jung section suffered heavy losses, a treaty was signed in 289, under which the Mu-jung tribe of the Hsien-pi recognized Chinese overlordship.  The Mu-jung were driven to this step mainly because they had been continually attacked from southern Manchuria by another Hsien-pi tribe, the Yue-wen, the tribe most closely related to them.  The Mu-jung made use of the period of their so-called subjection to organize their community in North China.