Sima Yi's Liaodong campaign
'''Sima Yi's Liaodong campaign''' occurred in 238 AD during the
Three Kingdoms period of
Chinese history.
Sima Yi, a general of the state of
Cao Wei, led a force of 40,000 troops to attack the kingdom of
Yan led by warlord
Gongsun Yuan, whose clan had ruled independently from the central government for three generations in the northeastern territory of
Liaodong (present-day eastern
Liaoning). After a siege that lasted three months, Gongsun Yuan's headquarters fell to Sima Yi with assistance from
Goguryeo (one of the
Three Kingdoms of Korea), and many who served the Yan kingdom were massacred. In addition to eliminating Wei's rival in the northeast, the acquisition of Liaodong as a result of the successful campaign allowed Wei contact with the non-Han peoples of
Manchuria, the
Korean Peninsula, and the
Japanese archipelago. 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.
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