7 _The role of the Uighurs. Confiscation of the capital of the monasteries_ This rising and its sequels broke the power of the dynasty, and also of the empire. The extremely sanguinary wars had brought fearful suffering upon the population. During the years of the rising, no taxes came in from the greater part of the empire, but great sums had to be paid to the peoples who had lent aid to the empire. And the looting by government troops and by the auxiliaries injured the population as much as the war itself did. When the emperor Su Tsung died, in 762, Tengri, the khan of the Uighurs, decided to make himself ruler over China. The events of the preceding years had shown him that China alone was entirely defenceless. Part of the court clique supported him, and only by the intervention of P'u-ku Huai-en, who was related to Tengri by marriage, was his plan frustrated. Naturally there were countless intrigues against P'u-ku Huai-en. He entered into alliance with the Tibetan T'u-fan, and in this way the union of Turks and Tibetans, always feared by the Chinese, had come into existence. In 763 the Tibetans captured and burned down the western capital, while P'u-ku Huai-en with the Uighurs advanced from the north. Undoubtedly this campaign would have been successful, giving an entirely different turn to China's destiny, if P'u-ku Huai-en had not died in 765 and the Chinese under Kuo Tzŭ-i had not succeeded in breaking up the alliance. The Uighurs now came over into an alliance with the Chinese, and the two allies fell upon the Tibetans and robbed them of their booty. China was saved once more.