At the end of the Eastern Han Dynasty, Gongsun lived in Liaodong, where he had no worries about food and clothing. The relationship between Koguryo and Gongsun Sheng was relatively harmonious at first, and they also sent troops to help him wipe out mountain thieves. However, in 196, when the new king of Koguryo ascended the throne, Baqi, brother B, got help from Gongsun Du and fought for the position and died. Since then, Koguryo and the Gongsun family have forged an issue. If Gongsun Sheng wants to enter the Central Plains, he must first solve Goguryeo's worries. If Koguryo wants to realize the expectation of dominating Liaodong, it must also eliminate the obstacle of Gongsun. Both of them have ulterior motives and are wary of each other. However, Koguryo is weak after all, and mainly adopts the defensive stance of protecting the environment and protecting the people, waiting for opportunities. When Gongsun Kang attacked Koguryo, it burned its capital and Koguryo was forced to move to Maruko (the mountain city west of Ji 'an, Jilin).

One of Goguryeo's diplomatic measures towards the Gongsun family was to establish a far-reaching relationship with Wu He. In 233, Wu Dong sent envoys to Gongsun Yuan and Liaodong. Later, Gongsun Yuan turned against him and killed two ambassadors. Some messengers fled to Koguryo, pretending to be ordered by Sun Quan. From then on, Goguryeo and Soochow once made friends, and Soochow also gave Goguryeo Dongchuan the title of "Khan". But it didn't last long. Of course, Cao Wei doesn't want to see this relationship continue to develop. He frequently sent envoys to Koguryo, urging it to break diplomatic relations with Soochow. A few years later, under the pressure of Wei, Goguryeo broke up with Wu, beheaded Hu Wei, the envoy of Wu, and sent his head to Youzhou.

The situation is developing rapidly. With Zhuge Liang's death in Wuzhangyuan, the pressure on the southwest front of Wei was relieved, and he began to make free his hands to clean up the unruly Gongsun Yuan. In 237, Sima Yi led 40,000 troops to land and sea in Liaodong, and asked Goguryeo to send troops to help. Goguryeo sent a master book with thousands of elite soldiers to help Wei Jun fight. A few months later, Xiangping City was broken, Gongsun Yuan died of cold water, and Gongsun Yuan's power in Liaodong collapsed. Wei Jun immediately dived into the sea and captured Le Lang and Daifang counties. Wei established Pingzhou in the area under the jurisdiction of the former Gongsun family, governing Liaodong, Changli, Xuantu, Daifang five counties, and appointed Yu Xiangping, Taiwei of Dongyi, as the governor.

After the downfall of the Gongsun family, all the counties in Liaodong fell into the hands of Cao Wei. At that time, Cao Wei was too busy with the wars of Wu and Shu to review. Goguryeo is up to no good. King Dongchuan wanted to dominate Liaodong instead of Gongsun, and sent troops to attack Pingxian County in Liaodong. Goguryeo minister Pepe had to go on a hunger strike to persuade Dongchuan king not to anger Cao Wei, so as to avoid national subjugation, but Dongchuan king did not listen to the advice. Soon, the battle between Wu Shu and Shu was settled, and Wei sent the East to take revenge on Koguryo.