Goguryeo territory as protector general. Furthermore, Emperor Gaozong was much ailing, so Empress Wu took a pacifist policy, and the Tang Empire was diverting resources towards other priorities. This situation favored Silla, because soon Silla would have to forcibly resist the imposition of Chinese rule over the entire peninsula, and there was much resistance to Tang rule (fanned by Silla, which was displeased that Tang did not give the Goguryeo territory to it), and in 669, following Emperor Gaozong's and Empress Wu order, a part of the Goguryeo people were forced to move to the region between the Yangtze River and the Huai River, as well as the regions south of the Qin Mountains and west of Chang'an, only leaving old and weak inhabitants in the original land. In 670, Wu's mother, Lady Yang, died and by Emperor Gaozong's and Empress Wu orders, all of the imperial officials and their wives attended her wake and mourned her. Later that year, with the realm suffering from a major drought, Empress Wu offered to be deposed which Emperor Gaozong rejected, so she remained his empress and continued to exercise power by "speaking to him" (like a co-ruler) or "on his behalf" (de facto regent). At her request, He further posthumously honored Wu Shiyue (who had previously been posthumously honored as the Duke of Zhou) and Lady Yang by giving them the titles of the Prince and Princess of Taiyuan. Xianheng era (670–674) In summer 670, the Tibetan Empire captured the 18 prefectures that Tang had established over the Western Regions (Xiyu), and Emperor Gaozong, in response, commissioned Xue Rengui, assisted by Ashina Daozhen () and Guo Daifeng (), to attack the Qinghai Lake area, to try to open a second front against the Tibetan Empire as well as to try to restore the territory previously held by Tuyuhun. However, Guo, who felt himself to be Xue's equal as a general, was displeased at serving as an assistant, and their discord eventually led to a major defeat at the hands of the Tibetan Empire's prime minister Gar Trinring Tsendro. For the time being, the Xiyu territory was lost. By 672, Emperor Gaozong gave up the hopes of reestablishing Tuyuhun and moved Murong Nuohebo and his people deep into Tang territory. By 674, Emperor Gaozong and Empress Wu was displeased at King Munmu of Silla encouragement of Goguryeo revival movements who continued to resist