When Qin and Qi were at a fierce war, Zhao had an opportunity to develop. At that time, Zhao Wuling, the monarch of Zhao State, was able to disagree with the public and learn from the Xi Hu people, known in history"Hufu cavalry shooting"。
At that time, there were Donghu in the northeast of Zhao State, and Linhu and Loufu in the northwest, all of whom were nomadic people in the north and were good at riding horses and archery. At that time, the troops of the Seven Kingdoms were basically chariot troops, and King Wuling of Zhao found that the chariot troops were not as fast as the nomads riding horses, and the chariots could not pursue the nomadic cavalry in the war, so he made up his mind to learn the tactics of the Xi Hu people.
Passed"Hufu cavalry shooting", Zhao established a strong cavalry force and quickly became stronger, able to confront Qin and Qi. In order to fight against Zhao, Qin sought an alliance with Qi. In 288 B.C., King Zhao of Qin called King Qi Emperor at the same time, Qin was the Western Emperor and Qi was the Eastern Emperor, preparing to unite the five kingdoms to attack Zhao and divide the land of Zhao into three parts.
Su Qin advised King Qi not to be the emperor, and King Qi listened to Su Qin's suggestion, abolished the emperor title, and Su Qin initiated a joint column, and the Qi State joined forces of Yan, Han, Wei, and Zhao to attack Qin to the west, forcing King Qin Zhao to also give up the emperor title, and return the land of Wei Zhizhao State occupied by Qin to them.