淝河
By 376 CE, the North had been reunified under the state of Former Qin, putting Jin in grave danger. In 383 CE, Fu Jian, ruler of Former Qin, invaded Jin with 300,000 troops, against which the Jin could only deploy 80,000 troops. However, the Chinese troops were well-trained and equipped, while the Qin army was made up mostly of conscripts. In the Battle of Fei River, the Qin army was routed by the Jin army.