The State of Yan was founded in the early Western Zhou Dynasty, around the 11th century BC, and was one of the earliest feudal states of the Western Zhou Dynasty with the surname Ji. Why did the Zhou Dynasty implement a sub-feudal system? The "Zuo Chuan" replied with eight words, "Feudal relatives, to the screen week". This means that the reason why the Western Zhou Dynasty wanted to implement the division of feudalism was to divide those who were closest to the Zhou royal family, that is, the heroes and relatives, to various places, and to establish a number of strongholds that could be controlled by the Zhou people, and to act as a barrier next to the Zhou royal family. So, how many princes were sealed in the early Western Zhou Dynasty? The "Zuo Biography" says, "King Keshang of Xiwu, there are only five people in the kingdom of his brothers, and forty people in the country of Ji are all relatives." "Xunzi" said, "At the beginning of the Zhou Dynasty, the world was ruled, seventy-one countries were established, and fifty-three people with the surname Ji lived alone." ”
In fact, whether it was the Fifty-Five Kingdoms or the Seventy-One Kingdoms, the honorable status of the first generation of monarchs of the Yan Kingdom was incomparable to that of any princely monarch except for the founding monarch of the State of Lu, Zhou Gong. "Zhou, zhao divided and ruled Shaanxi" is the best commentary. In short, the military and political power east of present-day Sanmenxia was coordinated by the Duke of Zhou; the area west of Sanmenxia, that is, the area around Guanzhong, where the Zhou people arose, was under the responsibility of the Duke of Zhao. Why was the Duke of Zhou able to quell the "Rebellion of the Three Prisons" launched by Wu Geng, the son of King Huan, and after the victory, he carried out a huge eastern expedition for three years, and the grain provided by the Duke of Zhao was the first to be credited. To this day, a poem of "Gantang" included in the Book of Poetry can still show the professionalism of the summoning of the public to govern Xi'an. However, although the history of the State of Yan is long, the historical data on its early situation is extremely scarce, so that several monarchs of the State of Yan after the Zhao Gong, except for the sentence in the "Records of History", "from the ninth emperor to the Huihou Of the Summoning Duke", have not even left a record of their names. But why did the yan state have more historical materials when it came to Yan Huihou? Because during the yan huihou period, an earth-shattering event occurred in western Zhou, that is, the "rebellion of the people of the country" in 841 BC.
As mentioned above, after the Zhou Dynasty destroyed the Shang, the Yin Shang remnants were not willing to fail and launched a large-scale rebellion. In order to put down the rebellion, the Zhou Dynasty had to transfer the elite troops from the Guanzhong region to the eastern battlefield, thus making the Rong people active in the northern Shaanxi Plateau large. Now, there was a rebellion in the Western Zhou Dynasty, which undoubtedly weakened the national strength of The Western Zhou again. Therefore, the Zhou royal family could no longer provoke the heavy responsibility of resisting the invasion of the Chinese princes by the Rong clan. This was fatal to the Yan state that founded the northern frontier. In fact, in 664 BC, the Yan state was indeed facing the danger of subjugation. Fortunately, at this time, the Duke of Qi Huan rose, and he not only led his army to repel Shanrong in time, but also generously donated a piece of Qi territory to the Yan state. However, the friendship between the Yan and Qi states was limited to the Spring and Autumn period, and by the Warring States period, which was dominated by annexation, the conflict between the two neighbors intensified, especially in 316 BC.
In that year, there was a "rebellion of the sons" in the Yan kingdom, and the state of Qi took advantage of the fire and robbery to attack and destroy it. However, because the State of Qi broke the strategic equilibrium of the seven heroes and heroes, it was immediately opposed by the nations, so that it finally returned without success. And the Yan Kingdom? Under the leadership of the new monarch Yan Zhao, everything started from scratch. After that, the history is familiar, and King Yan Zhao, later striving to become stronger, not only used Le Yi to avenge the destruction of the state of Qi, but also used troops to the north of Donghu to expand his territory to the area of present-day Liaodong. It can be said that the Yan Kingdom during the reign of King Yan Zhao can be called the most prosperous period since the establishment of the Yan State. But the hero of King Zhao does not mean that his successor monarch is also the same, such as Ji Xi, the last monarch of the Yan Kingdom.
Historical records record that on the eve of the imminent launch of the unification war in the Qin state, this stupid King of Yan could not see the situation clearly, and even did not listen to the dissuasion of the ministers, and again sent troops to fight the Zhao state after the defeat of Changping. It was also at a time when Yan and Zhao were fighting endlessly, the State of Qin quietly advanced under the eyes of the Zhao capital Handan, and completed the preparations for the destruction of the State of Zhao. At this time, Yan Guo saw clearly his situation. So, how can the Yan Congress eliminate the imminent danger of annihilation?
Ji Dan, the crown prince of the State of Yan, thought that assassinating the King of Qin and causing chaos in the Qin Kingdom was a good choice! However, his master Taifu Juwu thought that this plan was too presumptuous and had little chance of success. Therefore, he gave the suggestion of "the three Jin Dynasties in the west, the Qi and Chu in the south, and the Xiongnu in the north".
"The three Jin Dynasties in the west and the Qi and Chu in the south", according to the situation at that time, the chances of success were not high. Because at this time, the Three Jin Dynasties only had one Wei state, and although the Zhao state had a clan prince Jia Liguo in the daidi, its strength could only protect itself. The State of Qi has always pursued the strategy of making good friends with the State of Qin, and it is not easy to make sense of it. What about the Chu state? It has just experienced a seizure of power, and the new monarch has not yet stabilized the situation. Therefore, after hearing this, Prince Dan, who was familiar with the situation, told Ju Wu bluntly: This plan was protracted and costly. In fact, Prince Dan did not think deeply about Ju Wu's proposal of "Northern Xiongnu" in the second half of juwu. When used well, it can contain the main force of the Qin army and delay the pace of the Qin state's eastward exit.
We know that after the fall of the Zhao state, its territory around the Yinshan River Loop had nominally belonged to the Qin state. However, due to the need to destroy the country from the east, the Qin army did not invest too many troops here. Therefore, many of the nomadic people who had been expelled by Li Mu had returned to their homeland, especially the fierce and courageous Xiongnu, who once pushed the pastoral land to the vicinity of the Great Wall built by King Qin Zhao, that is, the Area of Helan Mountain. That is to say, using this as a supply base, the Xiongnu's rangers could infiltrate into Guanzhong through the Qingshui River Valley, the Jingshui River Valley, and the Malian River Valley. In addition, the Xiongnu of the Yinshan River Loop could also cross the Ordos steppe and go south to Guanzhong through the Luoshui River Valley and its tributaries. In fact, according to the history of warfare between the Han and The Huns for more than a hundred years, the Xiongnu cavalry was extremely mobile, and it was difficult for the Qin army, which had most infantry, to intercept on the long Line of defense on the Great Wall. Therefore, if Crown Prince Dan could heed Ju Wu's advice and persuade the Xiongnu to dispatch elite attacks to disturb the border of the Qin state with heavy gold, the Qin people would also send back a considerable part of the eastern army to protect the safety of Xianyang.
Reference: Chronicle of History