cause
After the first defeat in the fourth year of Longan (AD 400), the Western Qin Dynasty was destroyed in the fifth year of Longan (AD 40 1 year), and its national strength increased greatly, making it the most powerful country in the northwest at that time.
In the fifth year of Yixi, the eleventh year of the late Qin Dynasty and the third year of the prosperous Xia Dynasty (AD 409), Qin and Xia went to war one after another. In April of that year, he led 20,000 cavalry to attack Qin, plundered more than 7,000 miscellaneous households in Pingliang, and entered Ilichuan (now near Pingliang, Gansu).
In September, Yao Xing, king of Qin, led an army to counterattack Xia Jun, and Qin Jun was defeated. Yao Yusheng, the Qin general, was captured alive for Xia Jun, while Yao Wenchong, the left general, died. This just let Xia Jun retreat and Yao Xing return to Chang 'an. Then Xia Jun captured Qiqibao, Huangshigu, Luocheng and other places in the late Qin Dynasty.
In the sixth year of Yixi, the twelfth year of Hongshi at the end of Qin Dynasty, and the fourth year of Xia Longsheng (AD 4 10), Zhu Xia sent the left general Helian Luoti to capture Dingyang City at the end of Qin Dynasty (now Fuxian County, Shaanxi Province) and kill 4,000 people in Qin Jun. Then Xia Jun attacked Longyou area and captured Baiya Castle, which was almost equal to Qingshui (now Qingshui, Gansu Province).
Yixi was seven years old, Xia Longsheng was five years old, and later Qin Hongshi was thirteen years old (AD 4 1 1). In the first month, Qin Yao was forced by Xia Jun to abandon the city and flee. Xia Jun came after Yao Xiang and captured his whole army. Helian Bobo, the commander of the Xia Dynasty, attacked Anding in the south (now far south of Gansu Town), defeated Xiangfan Song, a post-Qin minister, in the north of Qingshi, and captured 45,000 officials.
In the 12th year of Yixi and 4th year of Xia Fengxiang (AD 4 16), in June, Xia Jun captured Shangbang, killed more than 5,000 people including the secretariat of Yao, destroyed Bangcheng, and then attacked Yinmi (now five miles west of Lingtai, Gansu), killing more than 65,000 people under Yao, the general of Qin.
Yao Hui, the general of Qin Zhengbei, abandoned Anding (now Jingchuan North, Gansu Province) and ran back to Chang 'an. Hu Yan, a steady man, led 50 thousand people to lift the city to summer. The successive years of conquest between the end of the Qin Dynasty and the Great Summer further consumed and weakened Qin Jun's strength and created favorable objective conditions for the Qin Dynasty after the demise of the Eastern Jin Dynasty.
After the defeat of Southern Yan in the Eastern Jin Dynasty, Liu Yuyuan wanted to attack the post-Qin Dynasty, but because the peasant uprising army led by Lu Xun and Xu Daofu approached Jiankang (now Nanjing, Jiangsu Province), the court urgently dispatched Emperor Wu of Song to return to suppress the peasant uprising army. Therefore, the Eastern Jin Dynasty had to postpone the timetable of defeating the later Qin Dynasty.
In the 11th year of Jin Dynasty (AD 4 15), Emperor Wudi successively suppressed the rebels of Lu Xun and Xu Daofu, and cut off the secretariat of Zhuge Changmin, the secretariat of Liu Fan, Jingzhou and Yuzhou. , Shu Shu was destroyed, and Sima Xiuzhi, the imperial clan of the Jin Dynasty, was hit. The political situation was stable and the economic and military strength was gradually enhanced.
At the beginning of the 12th year of Yixi (AD 4 16), Yao Bi, Yao Qing, Yao Xuan, Yao Genger, etc. Competing for the throne, political turmoil, floating people's hearts and increasing defectors. After years of battles with Hu Xia, Nan Liang and Xi Qin, the national strength was severely weakened and the status of a powerful country was lost. All these created favorable conditions for the destruction of Qin in the Eastern Jin Dynasty. Based on this, Emperor Wu of Song decided to send troops to destroy Qin.