During the Warring States period, after a long-term separatist war, the format of the rise and fall of vassal States changed greatly, and many weak countries were eliminated. There are only seven vassal states in China, namely Qi, Chu, Yan, Han, Zhao, Wei and Qin, which are called the Seven Heroes of the Warring States in history. The formation of "Seven Heroes" situation is not only the result of the annexation war since ancient times, but also the prelude to the reunification of China. In order to strengthen the national strength, the Seven Chivalrous Men launched a political reform activity in the fertile Qiang Bing. Wei appointed, Chu appointed Wuqi, and Zhao appointed Wuling, but the most effective thing was Qin's Shang 'an reform. In 359 BC, Qin Xiaogong appointed Shang Yang to carry out political reform and gradually became stronger. During the 65,438,000 years from Qin Xiaogong to the reign of the King of Qin, the national strength of Qin became stronger and stronger. In terms of the military system, conscription is carried out in counties, which improves the military organization and improves the combat effectiveness of the army. The soldiers are brave and brave in riding, far from being comparable to other six countries. In military strategy, it changed the strategy that laborers often lost in expeditions, and adopted Fan Sui's strategy of attacking from afar and attacking from near, gradually occupying and consolidating its occupied areas and implementing effective occupation. Qin successively destroyed the Western Zhou Dynasty and the Eastern Zhou Dynasty, captured the areas east and south of the Yellow River in South Korea, and set up Taiyuan, Shangdang and Sanchuan counties, covering most of Shaanxi, south-central Shanxi, western Henan, western Hubei, northwest Hunan and northeast Sichuan.
According to historical records, the state of Qin "has Bashu Hanzhong in the west, Hu Xun Ma Dai in the north, Wushan in the south and the benefit of solid trust in the east", which can be attacked and defended geographically; "A thousand chariots ride and hit a million", and its military strength far exceeds that of the other six countries.