as heir to
the throne because he was not the eldest son. The result of this was
tension between Li Shih-min and his father and brothers, especially the
heir to the throne. When the brothers learned that Li Shih-min was
claiming the succession, they conspired against him, and in 626, at the
very moment when the western Turks had made a rapid incursion and were
once more threatening the Chinese capital, there came an armed collision
between the brothers, in which Li Shih-min was the victor. The brothers
and their families were exterminated, the father compelled to abdicate,
and Li Shih-min became emperor, assuming the name T'ai Tsung (627-649).
His reign marked the zenith of the power of China and of the T'ang
dynasty. Their inner struggles and the Chinese penetration of Turkestan
had weakened the position of the Turks; the reorganization of the
administration and of the system of taxation, the improved transport
resulting from the canals constructed under the Sui, and the useful
results of the creation of great administrative areas under strong
military control, had brought China inner stability and in consequence
external power and prestige. The reputation which she then obtained as
the most powerful state of the Far East endured when her inner stability
had begun to deteriorate. Thus in 638 the Sassanid ruler Jedzgerd sent a
mission to China asking for her help against the Arabs. Three further
missions came at intervals of a good many years. The Chinese declined,
however, to send a military expedition to such a distance; they merely
conferred on the ruler the title of a Chinese governor; this was of
little help against the Arabs, and in 675 the last ruler, Peruz, fled to
the Chinese court.

The last years of T'ai Tsung's reign were filled with a great war
against Korea, which represented a continuation of the plans of the Sui
emperor Yang Ti. This time Korea came firmly into Chinese possession. In
661, under T'ai Tsung's son, the Korean fighting was resumed, this time
against Japanese who were defending their interests in Korea. This was
the period of great Japanese enthusiasm for China. The Chinese system of
administration was copied, and Buddhism was adopted, together with every
possible element of Chinese culture. This meant increased trade with
Japan, bringing in large profits to China, and so the Korean middleman
was to be eliminated.

T'ai Tsung's son, Kao Tsung (650-683), merely carried to a conclusion
what ha