 Complete the following phrase:  In 237, the Wei emperor Cao Rui felt insecure about Gongsun Yuans influence in the northeast, so he sent the general Guanqiu Jian to lead an army of Chinese, Wuhuan and Xianbei troops to attack Gongsun Yuan, but floods caused the campaign to be aborted. Gongsun Yuan declared himself King of Yan  and concluded an alliance with Eastern Wu. The following year, the Wei generals Sima Yi and Guanqiu Jian led a 