Qin Mugong supported the Jin Huigong, the Jin Huaigong and the Jin Wengong, and the three generations of the Jin State were all married to the Qin State, although there were occasional confrontations between the Qin and The Jin, on the whole it seemed friendly, and there was also a saying in history about this period, that is, the so-called "good of Qin and Jin". Any diplomatic relationship between countries is born of interests, and as the desire of the Qin state to move east is expanding day by day, and the Jin state becomes the hegemon in the east, the relationship between Qin and Jin is undergoing subtle changes. In 630 BC, the State of Jin joined forces with the State of Qin to besiege the State of Zheng, and as a result, Qin Mugong withdrew his army privately due to his interests, and a huge crack was created in the "goodness of Qin and Jin". The monarchs and courtiers of the Jin Dynasty were full of resistance to the Qin State, and the Battle of Kun, presided over by the Jin people in the Jin Xianggong era, became a sign of the end of the "Good of Qin and Jin", and since then there have been wars between Qin and Jin.
After the "good of Qin and Jin" broke down, the Qin people never gave up the opportunity to go east. Because the position of the Jin state in the east is stable, with the strength of the Qin state to dominate the Jin state, it is obviously not enough, especially in the Battle of Kun, the entire army of the Qin state was annihilated for the Jin state, and Qin Mugong's understanding of the Jin state was further advanced. After that, Qin Mugong set his sights on the West, more in the west, and for the Jin state Qin Mugong chose a better way to guard against it, that is, to unite with the Chu state. Qin and Jin had allied forces to attack the Chu vassal State of Guo, and the State of Chu sent the troops of Shen Gongziyi and Xi Gongzibian to garrison the State of Chu, but as a result, the State of Chu surrendered because it was afraid of the qin and Jin forces. The "Left Biography" says: "Imprisoning Shen Gongziyi and Xi Gongzi bian yigui", Shen Gongziyi and Xi Gongzibian were captured and returned to the Qin state, and these two princes became an excuse for Qin Mugong to ally with the Chu state.
And this Shen Gongziyi was actually very important in the Chu State, he was a descendant of the Gong clan of the Chu State, and was a descendant of the famous Ruo Ao clan of the Chu State. Therefore, when Shen Gongziyi was captured in the Qin Kingdom, most of the sons of ruo Ao clan would try to save him, but qin and Chu were separated by hundreds of miles, and there were still a number of small countries in the middle, the so-called guanshan mountains were heavy, and there were thousands of difficulties and obstacles, and the Chu people had not yet broken through the pass of the northward advance, and it was so difficult to rescue Shen Gongziyi. When Qin Mugong took the initiative to let go of Shen Gongziyi, at least the sons of the Ruo'ao clan who had the right to speak in the Chu State Court were quite concerned about allying with the Qin State. Even Shen Gongziyi was willing to take the initiative to support the Qin state, return to the Chu state and then vigorously promote the diplomatic alliance between Chu and Jin. This Shen Gongziyi still played an important role in the Chu State, and after returning to the Chu State, he became the prince's teacher, which was definitely good for the relationship between Qin and Chu.
In 627 BC, when Qin Mugong sent a large army to sneak into the State of Zheng, it could be seen through the Tianzi capital Luoyi, which showed that this road was smooth, also because on this road there was a Jin army that was friendly with the Qin state. But Qin Mugong chose the wrong time, this time is the time when the Jin state mourns the whole country, Qin Mugong over-believes in the Jin people, thinking that the Jin people will not turn their faces with the Qin state, the Qin state is just invading a small country Zheng Guo that the Jin state has always been bullying, and this Zheng state is originally a two-faced and three-sword, never really became a vassal of the Jin state, Qin Mugong sent a large army to attack the Zheng state, to some extent or help the Jin state to solve the problem. Qin Mugong's true intentions, of course, are more than that, Qin Mugong is to completely open the road to the east.
Roughly in today's eastern Shaanxi, southwestern Shanxi, and northwestern Henan, it is precisely the intersection of the Qin, Jin, and Zhou Tianzi's sphere of influence, and Qin Mugong's intention to attack Zheng Guo is easy to see through, especially those generals who have been fighting on the battlefield for a long time, such as the jin state's predecessors, insist on complete annihilation of the Qin army, it is precisely because they are worried that the Qin people's deployment of forces on this passage will have a huge impact on the hegemony of the Jin state, and the occurrence of the Battle of Kun is inevitable. After this war, the "good of Qin and Jin" broke down, and the war between Qin and Jin for more than ten years still occurred in these areas, which shows how deep the obsession of the Qin people is. Since the Jin Dynasty, Jin Xiang, and then the Jin State were faced with the seizure of power by their vassals, and the internal affairs also affected diplomatic and military affairs, the Qin Kanggong of the Qin State continued to launch the Eastward War, and finally deployed military forces to the Henan region in the Battle of Qiangma, and the Eastern Road of the Qin State finally tore a hole.
The State of Qin is working hard, the State of Jin is defending, and what is the State of Chu doing? The Chu people had Bashu in the west, and many Zhou people in the north and east divided the princely states, such as Hanyang Zhuji and other states. From Hanyang Zhuji and other countries to the north, it is the land of Henan. Therefore, when the military strength of the Qin people advanced to the land of Henan and committed to the two major frontier states that broke into the Central Plains, the alliance between the Qin state and the Chu state was more stable. Subsequently, the Chu people and the Qin state jointly carried out military operations many times, such as the Battle of Annihilation in 611 BC, the king of Chu Zhuang later marched north, and the large army reached the edge of the Luoshui River, it was here that the king of Chu Zhuang won the Central Plains, and the road of the Chu people from the Nanyang Basin into the City of Tianzi Was penetrated, and there was already a Qin military garrison on this route. It was after this that the Qin people from Guanzhong to Luoyi, the Chu people from Nanyang to Luoyi, the barrier between the two countries on the road was broken, the Qin and Chu attack strategies against the Jin state achieved unprecedented success, and the king of Chu Zhuang became the first person in the south to curb the hegemony of the Jin state.