Tang rule over the region and he stripped King Munmu of all Tang-bestowed titles, including the title of King of Silla, and arbitrarily conferred them on King Munmu's brother Kim Immun () instead, commissioning Liu Rengui, assisted by Li Bi (李弼, Li Ji's brother) and the ethnically Mohe general Li Jinxing (), to escort Kim Immun back to Silla territory. However, King Munmu formally apologized and offered tribute, Emperor Gaozong and Empress Wu drawal and recalled Kim Immun. The Sassanian prince Peroz III fled to China during this time around 670. The Chinese Emperor, who allowed Sassanian refugees fleeing from the Arab conquest to settle in China. Late reign: Problems of succession Shangyuan and Yifeng eras (674–679) In 674, one of Empress Wu claims concerned the title and power of empress; arguing that the Emperor was called Son of Heaven (天子, Tiānzǐ), his wife should logically be called Empress of Heaven (天后, Tiānhòu). As a result, she linked her co-rule with divine right. Around the new year 675, Empress Wu submitted twelve suggestions. One was that the work of Laozi (whose family name was Li and to whom the Tang imperial clan traced its ancestry), Tao Te Ching, should be added to the required reading for imperial university students. Another was that a three-year mourning period should be observed for a mother's death in all cases, not only in those cases when the father was no longer alive. Moreover, degradation and rejection of flattering officials, allowing all officials to speak to the level of chancellors, promotion of competent mid-level officials, military expenses were reduced, taxes cut, salaries of deserving officials raised, retirees given a viable pension, and vast royal lands near the capital turned over to husbandry. Emperor Gaozong praised her for her suggestions and adopted them. In 675, Li Jinxing reached Silla territory with Mohe forces that submitted to Tang. However, Tang forces were repelled by Silla army at Maeso fortress. The emperor over the years suffered much more severe headaches from consuming many of the dangerous substances that Empress Wu ordered. Because he could not run the empire, power in the imperial court gradually passed to Empress Wu. Meanwhile, by this time, even more Emperor Gaozong was continuously suffering from a persistent headache, and he considered making Empress Wu regent, to gain all power. Both Hao Chujun and Li Yiyan objected strenuously, and Emperor Gaozong did not make