What is history: it is the echo of the past to the future, the reflection of the future on the past. - Hugo
In the early days of the Western Han Dynasty, due to the chu-Han war and the purge of a number of princes with different surnames, the combat effectiveness of the Han army was extremely limited, and coupled with the fact that Han Wangxin and the Xiongnu should cooperate with each other, Liu Bang was surrounded in the Battle of Baideng.
In fact, with the national strength of the Xiongnu at that time, even if Liu Bang's troops were completely annihilated, they would not be able to enter the Central Plains, which was a problem of snakes swallowing elephants.
Regarding the definition of Xiongnu, there has always been controversy, usually, it is believed that this is a northern nomadic people active in the Zhou Dynasty to the Eastern Han Dynasty, but I think that such a definition is not appropriate, Wang Guowei once examined, Xiongnu is actually a general term for many nomadic peoples in the north at that time.
During the Han Dynasty, Sima Qian recorded in the Chronicle of History that due to the rise of the Xiongnu, the former nomadic peoples were also regarded as Xiongnu. In fact, the Huns were probably not a single ethnic group, but a political alliance of nomadic peoples, and multiple nomadic peoples gradually merged.
Because the "Xiongnu" before this were vulnerable, in the Warring States period, the Zhao state of the Seven Heroes could hang the Xiongnu, and the Zhao general Li Mu once dealt a heavy blow to the Xiongnu with a small number of troops, so that the Xiongnu did not dare to repeat the crime after ten years.
After the establishment of the Qin state, Qin Shi Huang sent Meng Kuo to lead an army of 300,000 to expel the Xiongnu from the Hexi Corridor, but during this period, in addition to the completion of the unification of the Central Plains Dynasty, the northern nomads were also rapidly integrating, in order to prevent the Xiongnu from invading the south and invading the people of the Central Plains, the Qin Dynasty began to build the Great Wall on a large scale, which shows that the Qin Dynasty is still very jealous of the Xiongnu, otherwise there is no need to go to great lengths to build the Great Wall.
Some historians believe that in order to enrich the population, the Huns often went south to plunder the population and livestock, and the construction of the Great Wall greatly increased the difficulty of plundering from the south, so the various tribes of the Xiongnu often had to travel together, which further promoted the unity of the nomadic peoples.
In this process, the emergence of Mao Dun Shan Yu accelerated this trend, at that time more powerful than the Xiongnu tribe was dong hu, mo dun shan yu was originally very tolerant of dong hu, when dong hu relaxed its vigilance, launched a surprise attack, after eliminating dong hu, the overall strength of the Xiongnu increased greatly, and then mao dun took advantage of the situation to send troops, first expelled the Yue clan to the west, and then annexed the Lou Fu and other tribes to the south, and took advantage of the Chu-Han War when the Central Plains Dynasty had no time to look north, and took back the Xiongnu territory that the Qin Dynasty had seized.
Since then, many tribes have been conquered successively, and Mao Dun Shan Yu also became the first figure to unify the northern steppe and establish a powerful Xiongnu Empire, when the Xiongnu territory was very vast, according to historical records, Mao Dun Shan Yu had more than 300,000 troops who could pull bows and shoot arrows.
Although Mo Dun shan was so good that he pushed the nomadic grand alliance of the Xiongnu to the peak of history, this was not a perfect political system after all, internal strife was very large, and when they had a strong leader, they could unite, and if they lacked such a strong leader, they would fall apart.
In nomadic civilization, the fist is everything, the tribe lives by herding horses, there is no fixed land, where the grass grows well, where to graze, whoever has a strong fist has the right to choose.
For this nascent regime, only continuous internal integration and external encroachment is the right path, that is to say, they are also constantly learning Han culture, well aware of the difficulties of ruling agricultural civilization, when Mao Dun repeatedly attacked Han Wangxin (not Han Xin, the Marquis of Huaiyin), who was stationed in the north of the Han Dynasty, under a series of military pressures, Han Wangxin had to defect to the Xiongnu and continue to expand south.
Under such circumstances, Liu Bang personally led the Han army north, and in suppressing the rebellion of Han Wangxin, Liu Bang achieved a great victory in the early stages, so that Liu Bang was lightly attacked in the following battles, and before the main force arrived, Liu Bang was surrounded by Mo Dundan at Baishan Mountain.
At this time, Liu Bang broke through several times and was always fruitless, but it was not so easy for the Xiongnu to break through the Han army's defense line, and after more than seven days of stalemate, the Xiongnu army did not achieve results.
According to historical records, at that time, Liu Bang adopted Chen Ping's strategy at a time of great difficulty, by bribing Mo Dun Shan Yu's wife and concubine Fu Shi, and through the Fu clan to Give Mo Dun Shan Yu a pillow side wind, preaching great truth, moving with affection, knowing the reason, telling Mo Dun Shan Yu that once the Han army reinforcements arrived, I was afraid that the Xiongnu army would suffer heavy losses, on the other hand, even if the Han Dynasty army was defeated, it would not be able to live for a long time because of the water and soil.
Another theory is that Mao Dundan yu finally let Liu Bang a horse, because at that time, Han Wangxin's reinforcement of xiongnu troops was delayed, and Mo Dundan was worried that they had already defected to the Han army, so as to attack the Xiongnu, so the Han army went out of Baishan Mountain.
In fact, I think that whether the water and soil are not satisfied, or whether they are worried about the betrayal of Han Wangxin, Mo Dun Shan Yu was not prepared to annex the Han Dynasty's Jiangshan at all, nor did he have the determination to carry out a strategic decisive battle with the Han army, after all, the Xiongnu at that time had just completed integration, and the interior was not very strong, and Mo Dun Shan Yu was also worried that something had gone wrong.
Judging from the lessons of later history, Mao Dundan was worthy of being an eagle on the grassland, and when considering things, he really thought more comprehensively, and during the Southern and Northern Dynasties, Former Qin Zhijian once led an army of 800,000 people to the south, and the advantage was exhausted, and as a result, he was defeated at the Battle of Shuishui, and Former Qin was thus torn apart.
During the Five Dynasties and Ten Kingdoms period, the nomadic Khitan under the leadership of Emperor Taizong of Liao, once defeated the Later Jin, occupied Tokyo, and changed the name of the country to Daliao, intending to unify China, but after only two months of operation, they encountered a deadly resistance from the people of the Central Plains, and Liao Taizong had to lead the Khitan army back to the north.
It can be seen from here that it is not easy for nomads to completely defeat the agrarian civilization in the Central Plains, but even after defeat, it is difficult to rule effectively.