When South Korea annexed Zheng, its territory was the largest.
First, analyze the land occupied by South Korea. South Korea is located in the hinterland of the Central Plains, which can be said to be a treasure trove of geomantic omen. However, the thoroughfare of the Five Kingdoms is really a battleground for military strategists. Close to the three great powers (Qin); Zhou is also the son of heaven, with a small territory; South Korea really has no room for development, so it can only bully Zheng while not paying attention. The part where South Korea invaded Wei in the above picture is the land acquired after the annexation of Zheng. In the first 353 years, when Korea invaded the Eastern Zhou Dynasty, it annexed Lingguan and Qiu Lin, which were not large enough on the map.
As one of the Three Jin Dynasties, Wei often fought with South Korea. A large area of South Korea was annexed by Wei. Look at the comparison below. Wei and Qin annexed a large area of South Korea. In 260-262 BC, after the battle of Changping, the State of Qin annexed Shangdang. South Korea is weakening again. The picture below intuitively shows that South Korea was beaten, leaving only one "sausage".
The warring States period was originally an era of war and disputes, and all countries wanted to annex each other; Unfortunately, South Korea's neighbors were all countries with the strongest military strength at that time, and it was really difficult for a relatively weak South Korea to survive in the cracks.
Moreover, the prosperity and demise of Korea are also related to rich mineral resources. Korea is also rich in mineral resources, such as iron ore. Because of this, the weapons produced in South Korea can be said to be the most popular among countries. At that time, there was a saying that "the strongest bow and strength in the world came from South Korea", and the sword made in South Korea was also "breaking cattle and horses, breaking water and breaking geese". This kind of resource is a battleground for military strategists.
Finally, from the internal analysis, South Korea is too self-destructive. Being in a battleground for military strategists and surrounded by powerful countries, South Korea should "build high walls and accumulate food". However, South Korea did not. South Korea has always been a strong side and a weak side. When Wei was powerful, Han Lian and Zhao Wei attacked Chu; United Wei and Zhao to cut Qi; United Wei to attack Qin. When Chu became strong, he joined forces with Chu to attack Wei. Every time a big country hits South Korea, it will cede territory. This practice in South Korea is really suicidal.
In 233 BC, the king of Han received the local title of Qin, asked him to be a vassal, and asked Han Fei to hire Qin. Directly recognized cowardice and gave talent to Qin.
23 1 BC: In order not to prevent Qin from sending troops to Hanguguan, Han presented Nanyang land to Qin.
Korea is really speechless. Talents were given to Qin, and such an important military town was also dedicated to Qin. Qin Jun is equivalent to the capital of South Korea. At this point, the king of Qin really had no reason not to kill him first.
In 230 BC, Shi Teng, the leader of the Qin school, suddenly crossed the Yellow River and attacked Zheng, the capital of South Korea (now Xinzheng, Henan). Wang Han surrendered and South Korea perished. Qin established Yingchuan County in North Korea.