The small states in the west, in Kansu (the Later Liang and the Western, Northern, and Southern Liang), were trading states: they lived on the earnings of transit trade with Turkestan. The eastern states were warrior states, in which an army commander ruled by means of an armed group of non-Chinese and exploited an agricultural population. It is only logical that such states should be short-lived, as in fact they all were. Sociologically regarded, during this period only the Southern and Northern Liang were still tribal states. In addition to these came the young Toba realm, which began in 385 but of which mention has not yet been made. The basis of that state was the tribe, not the family or the individual; after its political disintegration the separate tribes remained in existence. The other states of the east, however, were military states, made up of individuals with no tribal allegiance but subject to a military commandant. But where there is no tribal association, after the political downfall of a state founded by ethnical groups, those groups sooner or later disappear as such. We see this in the years immediately following Fu Chien's collapse: the Tibetan ethnical group to which he himself belonged disappeared entirely from the historical scene. The two Tibetan groups that outlasted him, also forming military states and not tribal states, similarly came to an end shortly afterwards for all time. The Hsien-pi groups in the various fragments of the empire, with the exception of the petty states in Kansu, also continued, only as tribal fragments led by a few old ruling families. They, too, after brief and undistinguished military rule, came to an end; they disappeared so completely that thereafter we no longer find the term Hsien-pi in history. Not that they had been exterminated. When the social structure and its corresponding economic form fall to pieces, there remain only two alternatives for its individuals. Either they must go over to a new form, which in China could only mean that they became Chinese; many Hsien-pi in this way became Chinese in the decades following 384. Or, they could retain their old way of living in association with another stock of similar formation; this, too, happened in many cases. Both these courses, however, meant the end of the Hsien-pi as an independent ethnical unit. We must keep this process and its reasons in view if we are to understand how a great people can disappear once and for all. The Huns, too, so powerful in the past, were suddenly scarcely to be found any longer. Among the many petty states there were many Hsien-pi kingdoms, but only a single, quite small Hun state, that of the Northern Liang. The disappearance of the Huns was, however, only apparent; at this time they remained in the Ordos region and in Shansi as separate nomad tribes with no integrating political organization; their time had still to come. 6 _Spread of Buddhism_