As we said before, Duke Mu of Qin considered the interests of the State of Qin and in order to avoid too many conflicts with the State of Jin, so he decided to marry the State of Jin. The alliance between Qin and Jin lasted for a long time, and it did bring some benefits to the Qin state. However, when the Qin and Jin countries united, when participating in the struggle for hegemony, it was more dominated by the Jin state, and the most profitable was also the Jin state. Qin Guo naturally did not want to be like a follower all the time. When Qin and Jin jointly attacked Zheng Guo, the Qin State privately negotiated peace with Zheng Guo's candles, harming the interests of the Jin State, and the Jin State naturally had opinions on this. The gap between the two countries became more and more obvious, but the alliance between Qin and Jin barely lasted until the death of Duke Wen of Jin.
After the death of Duke Wen of Jin, Duke Xiang of Jin succeeded to the throne. Duke Mu of Qin wanted to take advantage of the new monarch of the Jin Dynasty to succeed to the throne and compete for the position of overlord. Moreover, after making peace with Zheng Guo, the general Qi Zizi, who remained in Zheng Guo to help Zheng Guo guard, wrote to him, saying that he had mastered the defense of Zheng Guo's city and hoped that Qin Mugong would send troops to attack Zheng Guo as soon as possible, and that he would make internal responses in Zheng Guo, so that Zheng Guo could be taken by Qin Guo.
Qin Mugong, who was anxious to develop eastward, was impressed by Qizi's plan, and despite the repeated persuasion of the chancellor, he insisted on going his own way and ordered Meng Ming and other generals to lead an army to attack Zheng Guo. However, the State of Qin and the State of Zheng were far apart, and they needed to cross many countries on the way. As a result, the Qin army had just passed through the Zhou capital Luoyi, and it encountered Zheng Guoren, who was doing business in that area. While rewarding the Qin army in the name of Zheng Guojun, Xiang Gao quickly informed Zheng Mugong of the matter. After Zheng Mugong received the information, he went to the camp of Qizi and the others to inquire about the situation, and seeing that Qizi and the others were indeed ready for battle, he gently warned Qizi and the others, hoping that they would leave. When Qi Zi and the others saw that the matter had been exposed, they fled. Meng Ming saw that nei should be gone, and the army he led could not conquer the State of Zheng, so he planned to withdraw his army and return to the State of Qin. At this time, the army of the State of Qin was stationed in the Slippery State, which was a small country with weak combat effectiveness. Meng Ming felt that the Qin army had traveled thousands of miles to the Central Plains and returned empty-handed, so he conveniently destroyed the slippery country and returned home with the spoils of war.
When the Qin army returned to China, it needed to pass through the Kunshan Mountains of the Jin Dynasty. Kunshan is a steep fortress here. At the beginning, Uncle Jian and the others considered that the Qin State was going to pass through these places and was easy to be ambushed, so they tried their best to stop Qin Mugong. Now the Qin army was about to return from Kunshan, and it was indeed attacked by the Jin state.
When the State of Qin and Candle Zhiwu were privately talking about peace, some people in the State of Jin were dissatisfied with the State of Qin and asked Duke Wen of Jin to send troops to attack the State of Qin, but Duke Wen of Jin refused to consider the relationship between the two countries. However, the successor Duke Xiang of Jin had no intention of getting close to the State of Qin, and the calls within the State of Jin for a crusade against the State of Qin were also getting louder and louder. At this time, the Qin army was in the territory of the Jin state, giving the Jin state the opportunity to attack them. The State of Qin destroyed the State of Shui and the State of Jin had the same surname, that is to say, the State of Qin destroyed relatives of the State of Jin, which gave the State of Jin a reason to attack the State of Qin. Therefore, The Duke of Jin Xiang resolutely ordered that jiang Rong be united to ambush the Qin army at Mount Kun. The unsuspecting Qin army entered the ambush circle, and eventually the entire army was destroyed, and Meng Ming and others were captured. This is the famous Battle of Kun.
Meng Ming and the others were taken to the capital of the Jin Dynasty and were about to be executed. The stepmother of Duke Xiang of Jin, the wife of Duke Wen of Jin, the daughter of Duke Mu of Qin, claimed that Duke Mu of Qin wanted to personally execute Meng Ming and others, and deceived Duke Xiang of Jin into releasing three of them. After Meng Ming returned to China, Qin Mugong went out of the city dressed in white to greet him, assumed the responsibility for the defeat of the Qin army, and comforted Meng Ming, asking him to continue to train his troops.
After the Battle of Kun, the State of Qin broke with the State of Jin, and the road of the State of Qin to the east was completely blocked by the State of Jin. After that, after several years of cultivation, the State of Qin fought several wars with the State of Jin, and the results were not ideal. For the last time, Meng Ming invaded the Jin state with the determination to die in battle, recovered the lost land, and avenged the Battle of Kun that year. However, the strength of the Jin state was stronger than that of the Qin state after all, and Qin Mugong, seeing that the lost land had been recovered, ordered the battle to be stopped, and from then on it no longer developed to the east, but began to operate in the west, and at the same time contacted the State of Chu, allowing the State of Chu to contain the State of Jin in the east, and exempting the threat from the State of Jin.
Large tracts of land to the west of the Qin state were under the control of Xi Rong, and these Xi Rong tribes were not weak. Previously, the Qin state was bent on developing to the east, and did not attach great importance to the development of the western region. At this time, the road to the east had been blocked by the Jin state, and Qin Mugong changed his strategy and planned to incorporate the western region into the territory of the Qin state.
It was probably during this time that the stronger of the Xirong tribe, hearing that Qin Mugong was very capable, was afraid that the Qin state would be unfavorable to Xirong, so he sent Yu Yu to the Qin state to inquire into the truth. Yu's ancestors were Jin people who fled to Xirong for some reason. Yu Yu himself was very capable, so he was trusted by king Rong, and because he could speak the language of Jindi, he was sent out by king Rong.
Qin Mugong talked to Yu Yu and felt that Yu Yu was a rare talent, so he designed to separate Yu Yu and King Rong. Yu Yu lost the trust of King Rong and was forced to defect to the Qin state. Duke Mu of Qin received Yu Yu solemnly and discussed with Yu Yu every day the strategy of the crusade against Xi Rong. At Yu's suggestion, Qin Mugong destroyed more than a dozen small states of Xirong in a very short period of time, shocking the world for a while. When the King of Zhou heard this, he rewarded Qin Mugong with a golden drum to congratulate him and encouraged Qin Mugong to continue his crusade against Xi Rong to the west. With the affirmation of the King of Zhou, Qin Mu's ideal of hegemony was also realized.
Soon after dominating Xi rong, Qin Mugong passed away. But he had left enough capital for the Qin state. For a long time after that, the Qin state was committed to the development of the western region, and when the eastern countries attacked each other and consumed each other, because of the existence of the Jin state and because of the correct development strategy, the Qin state was not affected too much, and it entered the Warring States period relatively stably, and accumulated enough strength for the rise thereafter.