After the three families were divided into Jin, the jin state, which was once the overlord of the Central Plains, split into three countries, the Zhao kingdom, the Wei state, and the Korean state. Of the three, South Korea is the weakest.
There is no way, South Korea has the least amount of land, but it is still the most barren, and it is not suitable for farming at all. Moreover, his geographical terrain is not good, and it can be said that there is no danger to defend. Coupled with the fact that the east is the State of Qi, the south is the State of Chu, and the west is the State of Qin, if you do not pay attention to it, Korea will be in danger of being destroyed.
This worries Korea, after all, he has become a princely state with great difficulty, and he does not want to be eliminated so quickly. If you don't want to be wiped out, you need more strength. At that time, the most reflective of the country's strength was land and population, so Zheng Guo, who was located to the east of him, was targeted.
There was no way, the south was the Chu State, and he definitely couldn't beat it. In the surrounding Wei kingdoms, the first is a brother, and the second is that he can't beat it. As for the State of Qin and the State of Qi, he had no choice but to pick a soft persimmon.
This Zheng state, in the early Spring and Autumn Period, was the largest country, not only destroying many small countries around it, but also bullying the Song Kingdom, the Wei State, and the Lu State from time to time. Even if it was Qi Guo, when he was violently beaten by Beidi, it was still the field that Zheng Guo helped to find.
However, the first major country in the early Spring and Autumn Period turned out to be due to internal strife, which led to the weakening of national strength. Later, the Spring and Autumn Five Hegemons took turns to appear, and Zheng Guo actually became a warring place for all countries, which brought serious damage to Zheng Guo. Wait until the three families are divided into Jin and enter the Warring States period, then you can describe him as a lingering breath.
Although Zheng Guo has declined, after all, the skinny camel is bigger than Ma, and the territory and population he has are not much different from that of South Korea, which has just separated. In 423 BC, Zheng Yougong, the new boss of the State of Zheng, succeeded to the throne, and taking this opportunity, Korea sent troops to attack the State of Zheng. In order to resist the Korean attack, Zheng Guo also built a section of the Great Wall.
If it were not for the fact that in 407 BC, the State of Wei had summoned Korea to attack the State of Qi together, and it is not known how long they would fight again.
If Zheng Guo had taken advantage of this respite to quickly reorganize his armaments, he might have survived for decades. However, in 400 BC, zheng guo once again had civil unrest, Zheng Guo's boss killed the prime minister, the prime minister's younger brother killed the zheng guo boss, and then supported a new boss, so that the Zheng state once again fell into civil strife, and all the domestic forces were vying for power and profit.
This pleased Korea, and in 385 BC, Korea again attacked the Kingdom of Zheng. The war lasted until 375 BC, when Korea conquered the capital of the Zheng state, destroyed the Zheng state, and accepted the entire land and population of the zheng state. As a result, South Korea's national strength rose rapidly, and it had the capital to become the Sengoku Seven Heroes.
From the beginning to the end, it took South Korea nearly fifty years to destroy the Zheng kingdom, which shows that even if the Zheng state declines, it is not easy to deal with. If it were not for zheng's civil unrest, South Korea would not know how long it would take to take Zheng guo.
And if South Korea had not taken Zheng Guo, he really would not have been able to become one of the seven heroes of the Warring States, after all, in that era of the chaos of the princes, land and population were the key to whether they could become a strong country.