Some of these frontier tribes, notably the Tartars, were of altogether too tough a material to be assimilated. They even endeavoured to check the Chinese advance beyond the Yellow River, and carried fire and sword themselves into the federal conclave. Where resistance was _nil_ or slight, as, for instance, among some of the barbarians to the east, there the Chinese adventurers, either adopting native ways, or persuading the autochthones to adopt their ways, by levelling up or levelling down, developed strong cohesive power; besides (owing to the difficulties of inter-communication) creating a feeling of independence and a disinclination to obey the central power. The emperors who used in the good old days to summon the vassals--a matter of a week or two in that small area--to chastise the wicked tribes on their frontiers, gradually found themselves unable to cope with the more distant Tartar hordes, the eastern barbarians of the coast, the Annamese, Shans, and other unidentified tribes south of the Yang- tsz, as they had so easily done with nearer tribes when the Chinese had not pushed out so far. Moreover, new-Chinese, Chinese- veneered, and half-Chinese states, recognizing their own responsibilities, now interposed themselves as "buffers" or barriers between the Emperor and the unadulterated barbarians; these hybrid states themselves were quite as formidable to the imperial power as the displaced barbarians had formerly been. Hence, as we have seen, the pitiful flight from his metropolis of one Emperor after the other; the rise of great and wealthy persons outside the former limited sacred circle; the pretence of protecting the Emperor, advanced by these rising powers, partly in order to gain prestige by using his imperial name in support of their local ambitions, and partly because--as during the Middle Ages in the case of the Papacy--no one cared to brave the moral odium of annihilating a venerable spiritual power, even though gradually shorn of its temporal rights and influence.