In fall 563, Northern Zhou entered into an alliance treaty with the Gokturks, known to the Chinese ajs Tujue, against Northern Qi, part of which involved a promise that Emperor Wu would marry the daughter of Ashina Qijin, Tujue's Mugan Khan. In winter 563, the joint forces of Northern Zhou and Tujue launched a two-prong attack on Northern Qi, with the northern prong attacking Northern Qi's secondary capital Jinyang (晉陽, in modern Taiyuan, Shanxi) and the southern prong attacking Pingyang (平陽, in modern Linfen, Shanxi). The northern prong, commanded by the general Yang Zhong (), put Jinyang under siege, but was soon defeated by the Northern Qi general Duan Shao () and forced to withdraw. In response, the southern prong, commanded by Daxi Wu (), also withdrew. Still, the attack demonstrated the growing Northern Zhou strength—as previously, in the winter months, Northern Zhou forces would break the ice on the Yellow River to prevent possible Northern Qi attacks, but around this time and thereafter, Northern Qi forces broke the ice on the river to prevent possible Northern Zhou attacks.