During the Warring States period, Zhao confronted Xiongnu for a long time, and Tuoba Hu was brave and strong, better than Qin Luzhi's infantry. Although Zhao is rich in horses, militarily, horses are used to pull chariots. After the war with tarquin, King Wuling of Zhao realized that tarquin's advantage lies in its mobility and flexibility. The armies of the Seven Heroes in the Warring States Period, even the cavalry, were all equipped with heavy armor. On the contrary, the Xiongnu army is light in clothing, integrated with men and women, and has strong mobility, and can advance and retreat. So, with the support of Zhao Jungai, Minister Fei Yi and others, King Wuling of Zhao imitated the equipment of the Xiongnu army, made the people of the whole country put on Hu clothes, used Hu people's short jackets and shorts, and rode a horse with a bow to practice archery, which was a great breakthrough in China's military history.