About the time when the power of Khitan was deteriorating in Manchuria, Goryeo was once again troubled by the Jurchen. Goryeo sent an expedition but failed. Goryeo found that it was difficult to counter the mounted Jurchen with its foot soldiers alone. It was for this reason that Yun Gwan created a new military organization called Extraordinary Military Corps (Byeolmuban), which drove back the Jurchen to the north of the great wall of a thousand li, and built the so-called Nine Forts in the northeastern region. However, upon appeals from the Jurchen, Goryeo returned the region of the Nine forts to the Jurchen after it vowed never to invade Goryeo and to present offerings to Goryeo every year.
The Jurchen, which had become more powerful than ever before, founded a state called chin and claimed itself an empire. Through an alliance with Sung China, chin overcame the Khitan and eventually drove the sung down to the south. the chin put increased pressure on Goryeo as well, and demanded that Goryeo enter into a suzerainty relationship. Yi Ja-Gyeon, in power at the time, judged that peaceful relations with Chin would contribute to maintaining his own political dominance, and so he assented to Chin' s demands. As a result, Goryeo was able to maintain peaceful relations in the international arena. The northern expansion policy that had been promoted since the establishment of Goryeo, however, was temporarily suspended.