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 had been begun.  Externally China’s prestige continued at its zenith.  The caravans streamed into China from western and central Asia, bringing great quantities of luxury goods.  At this time, however, the foreign colonies were not confined to the capital but were installed in all the important trading ports and inland trade centres.  The whole country was covered by a commercial network; foreign merchants who had come overland to China met others who had come by sea.  The foreigners set up their own counting-houses and warehouses; whole quarters of the capital were inhabited entirely by foreigners who lived as if they were in their own country.  They brought with them their own religions:  Manichaeism, Mazdaism, and Nestorian Christianity.  The first Jews came into China, apparently as dealers in fabrics, and the first Arabian Mohammedans made their appearance.  In China the the foreigners bought silkstuffs and collected everything of value that they could find, especially precious metals.  Culturally this influx of foreigners enriched China; economically, as in earlier periods, it did not; its disadvantages were only compensated for a time by the very beneficial results of the trade with Japan, and this benefit did not last long.

4 The reign of the empress Wu:  Buddhism and capitalism

The pressure of the western Turks had been greatly weakened in this period, especially as their attention had been diverted to the west, where the advance of Islam and of the Arabs was a new menace for them.  On the other hand, from 650 onward the Tibetans gained immensely in power, and pushed from the south into the Tarim basin.  In 678 they inflicted a heavy defeat on the Chinese, and it cost the T’ang decades of diplomatic effort before they attained,