a had regarded herself as the only existing
civilized country, and all other countries had been regarded as
barbaric, for a civilized country was then taken to mean a country with
urban industrial crafts and agriculture. In our present period, however,
China's relations with the Middle East and with southern Asia were so
close that the existence of civilized countries outside China had to be
admitted. Consequently, when alien dynasties ruled in northern China and
a new high civilization came into existence there, it was impossible to
speak of its rulers as barbarians any longer. Even the theory that the
Chinese emperor was the Son of Heaven and enthroned at the centre of the
world was no longer tenable. Thus a vast widening of China's
intellectual horizon took place.

Economically, our present period witnessed an adjustment in South China
between the Chinese way of life, which had penetrated from the north,
and that of the natives of the south. Large groups of Chinese had to
turn over from wheat culture in dry fields to rice culture in wet
fields, and from field culture to market gardening. In North China the
conflict went on between Chinese agriculture and the cattle breeding of
Central Asia. Was the will of the ruler to prevail and North China to
become a country of pasturage, or was the country to keep to the
agrarian tradition of the people under this rule? The Turkish and Mongol
conquerors had recently given up their old supplementary agriculture and
had turned into pure nomads, obtaining the agricultural produce they
needed by raiding or trade. The conquerors of North China were now faced
with a different question: if they were to remain nomads, they must
either drive the peasants into the south, or make them into slave
herdsmen, or exterminate them. There was one more possibility: they
might install themselves as a ruling upper class, as nobles over the
subjugated native peasants. The same question was faced much later by
the Mongols, and at first they answered it differently from the peoples
of our present period. Only by attention to this problem shall we be in
a position to explain why the rule of the Turkish peoples did not last,
why these peoples were gradually absorbed and disappeared.

2 _Status of the two southern Kingdoms_

When the last emperor of the Han period had to abdicate in favour of
Ts'ao P'ei and the Wei dynasty began, China was in no way a unified
realm. Almost immediately, in 221, two oth