On the other hand, the war and the subsequent centralisation policies lessened the Chinese grip on the territory, which permitted a number of non-Han states to form in the area in later centuries.

Liaodong Commandery of You Province, part of present-day Northeast China, was situated at the northeastern fringe of Eastern Han Empire, surrounded by the Wuhuan and Xianbei nomads in the north and Goguryeo and Buyeo peoples in the east.

Taking advantage of his distance from central China, Gongsun Du stayed away from the chaos which accompanied the effective end of Han rule, expanded his territories to include the commanderies of Lelang and Xuantu, and eventually proclaimed himself as Marquis of Liaodong (遼東侯).

[6] Soon after Gongsun Yuan came to power in Liaodong, China was, for the most part, split into three: Cao Wei in the north, Shu Han in the southwest, and Eastern Wu in the southeast.

Cao Wei eventually got wind of the embassies and made one successful interception in Chengshan (成山), at the tip of the Shandong peninsula, but Gongsun Yuan had already sided with Sun Quan.

When the Wu embassy arrived, Gongsun Yuan seized the treasures, killed the leading ambassadors, and sent their heads and a portion of their goods to the Wei court to buy himself back to favour.

The king sent 25 men to escort the envoys back to Wu along with a tribute of sable and falcon skins, which encouraged Sun Quan to send an official mission to Goguryeo to further the two states' relations.

Cao Wei did not want to see Wu regain a diplomatic foothold in the north, and established its own connections with Goguryeo through the Inspector of You Province (幽州刺史) Wang Xiong (王雄).

From Wei's point of view, although the Xianbei insurrection by Kebineng had been put down recently, Liaodong's position as a buffer zone against barbarian invasions needed to be clarified.

With troops of You Province as well as Wuhuan and Xianbei auxiliaries, Guanqiu Jian crossed the Liao River east into Gongsun Yuan's territory and clashed with his enemy in Liaosui (遼隧; near present-day Haicheng, Liaoning).

In a series of contradictory actions, Gongsun Yuan memorialised the Wei court in hope of getting a pardon on one hand, while formally declaring independence on the other by assuming the title King of Yan.

But if he stays in [the Liaodong capital] Xiangping (襄平; present-day Liaoyang) and defends it, he will be captured... Only a man of insight and wisdom is able to weigh his own and the enemy's relative strength, and so give up something beforehand.

[21] Having heard of the new preparations made against him, Gongsun Yuan desperately dispatched an envoy to the Wu court to apologise for his betrayal in 233 and begged for help from Sun Quan.

At first, Sun Quan was ready to kill the messenger, but he was persuaded by Yang Dao (羊衜) to make a display of force and possibly gain advantages if Sima Yi and Gongsun Yuan became deadlocked in war.

Gongsun Yuan responded by sending Bei Yan (卑衍) and Yang Zuo (楊祚) with the main Liaodong force to set camp at Liaosui, the site of Guanqiu Jian's defeat.

Bei Yan caught up with Sima Yi in Mount Shou (首山), a mountain west of Xiangping, where he was ordered to fight to the death by Gongsun Yuan.

Since the defenders had been obtaining supplies with such ease during the flood, there apparently was not any real attempt to stockpile the goods inside Xiangping, and as a result famine and cannibalism broke out in the city.

A frightened Gongsun Yuan sent his Chancellor of State Wang Jian (王建) and Imperial Counsellor Liu Fu (柳甫) to negotiate the terms of surrender, where he promised to present himself bound to Sima Yi once the siege was lifted.

"[36][37] Apparently, Sima Yi's previous suggestion of further negotiations was nothing more than an act of malice that gave false hope to Gongsun Yuan while prolonging the siege and placing further strain on the supplies within the city.

A separate fleet, led by future Grand Administrators Liu Xin (劉昕) and Xianyu Si (鮮于嗣), had been sent to attack the commanderies of Lelang and Daifang on the Korean peninsula by sea, and in time, all of Gongsun Yuan's state of Liaodong was subjugated.

In addition, 7,000 people of age 14 and above who had served in Liaodong's army were put to death, their corpses heaped up to form a great mound meant to terrorise those who survived.

When someone pointed out that they had a surplus of ru (襦) and suggested giving them out to the soldiers, Sima Yi refused and said that the rus were the property of the Wei government and should not be distributed without permission.

[47] Although he had gained 40,000 households and some 300,000 people for the state of Wei from this expedition,[48][49] Sima Yi did not encourage these frontier settlers to continue their livelihoods in the Chinese northeast and instead ordered that those families who wished to return to central China be allowed to do so.

This happened around the same time as the Xianbei chieftain Mohuba was awarded merit for his participation in the campaign against Gongsun Yuan, and his people were allowed to settle in northern Liaodong.