Li Keyong
In summer, Li Keyong advanced south through Hedong Circuit, and he wrote then-military governor of Hedong, Zheng Congdang, requesting that Zheng supply his troops. Zheng, while not openly hostile to Li Keyong, was suspicious of him, and therefore closed the gates of Hedong's capital Taiyuan Municipality and refused to provide Li Keyong with anything more than limited supplies. Li Keyong responded by pillaging the Taiyuan region. Zheng then sought and received aid from Qibi Zhang (契苾璋) the military governor of Zhenwu, who launched Tuyuhun and Tujue soldiers to repel the Shatuo. Li Keyong was forced to withdraw north. He captured Xin (忻州, in modern Xinzhou) and Dai (present-day Daixian) Prefectures and made Dai his headquarters.