When Empress Dowager Gao died in 1093, Emperor Zhezong of Song asserted himself at court by ousting the political conservatives led by Sima Guang, reinstating Wang Anshi's reforms, and halting all negotiations with the Tanguts of the Western Xia. This resulted in continued armed conflict between the Song dynasty and the Western Xia. In 1099, the Northern Song launched a campaign into Xining and Haidong (in modern Qinghai province), occupying territory that was controlled by the Tibetan Gusiluo regime since the 10th century. By 1116, Song managed to acquire all of its territory and incorporated it into prefectures; the area became the westernmost frontier against the Western Xia.