the forts and surrounded by the enemy. The Jurchens asked that the nine forts be handed over and that a peace agreement be reached, and in May 1109 Yejong decided to accept, considering that in the meantime the Korean territory had been hit by famine and disease. Goryeo agreed to pay tribute to the Jurchens and withdrew all troops. From 994, Goryeo had been a tributary state of Khitan Liao, which was a dominant power in the region, and had consequently adopted its calendar and its official era names. As not to antagonize Liao, the relations with Song China had been conducted discreetly, but were resumed in 1062, and more frequently, with the decline of Liao's power, also signaled by the fact that Liao no longer collected tributes after 1054. Following the defeat to the Jurchens, Goryeo cultivated its relations with Song, while taking a neutral stance between Jurchens and Liao. In 1114 Yejong sent a request to Huizong asking for Chinese musical instruments to be sent to his palace in Gaeseong, so that he could conduct Confucian rituals. Huizong, apparently misunderstanding the request, sent a set of musical instruments to be used for royal banquet music. The gift included 167 instruments and 20 volumes of music and performance instructions. The following year, the Jurchen leader Wanyan Aguda proclaimed the establishment of the Jin dynasty with himself as its first emperor, Taizu. Liao asked Goryeo for help, but the request was refused because the view of the majority of Yejong's officials was that the Jurchen were going to emerge victorious and the Liao would fall soon. In 1116 a large embassy was dispatched to the Song court, while the second gift of musical instruments, consisting of 428 pieces had arrived, as well as ritual dance accessories and manuals, starting Korea's tradition of aak. Together with the gifts came a request to bring the Jurchen representatives to the Song court. It was declined, and Yejong warned Huizong not to deal with the Jurchen, because they "were like tigers and wolves". Trade and official contacts continued: in 1117 Song established a special office to deal with Goryeo merchants and envoys; furthermore, a large Chinese mission arrived in 1122, including the Confucian scholar Xu Jing (1091–1153), whose notes are an important source of information about the period. In 1117, the Goryeo army advanced to Ŭiju area at the Yalu River, reconquered the territory