Evicted by the defeats, Yizhixie Chanyu (伊稚邪) took Zhao Xin's advice, and the Xiongnu tribes retreated to the north of the Gobi Desert, hoping that the barren land would serve as a natural barrier against Han offensives. In 119 BC, Emperor Wu planned a massive expeditionary campaign. Chinese forces were deployed in two columns, each consisting of 50,000 cavalry and over 100,000 infantry. Wei Qing and Huo Qubing served as the supreme commanders, and set off from Dai Prefecture (代郡) and Dingxiang (定襄).