Why did Yan, the weakest state in the Warring States Period, beat Xiongnu, and why did the Western Han Dynasty struggle so hard?

Yan fought mainly against the Donghu tribe, not directly against the Huns. Zhao has been dealing with Xiongnu for a long time and fought with Xiongnu. However, in the face of Xiongnu and East Lake, the two countries are also defensive and dare not attack Xiongnu on the grassland easily. Li Mu, a famous soldier of the State of Zhao who fought against Hungary, was able to use strategic and geographical advantages to defeat the Xiongnu army at home.

Only at this level can the Han Dynasty do it easily. For example, at the beginning of the Han Dynasty, Xiongnu Khan rebelled against Mao Dun, Lu Wan, Yan Wang and Zhao successively, and the border and land were once opposed, which enabled Xiongnu troops to enter the mainland and even March into Taiyuan. But after all, at home, Liu Bang organized an army to counterattack, and three times five divided by two drove the Xiongnu out of Yanmenguan. Although Liu Bang was reckless because of his flying skills, he fell behind? The siege of Baden? Joke, but there is no denying that Liu Bang really drove the Huns out of the country easily. It can be said that the Xiongnu did not win much in fighting the Han army in the mainland.

It is different for the Han army to fight in the grassland. The supply line is a big problem, and the expedition is extremely painful for the Han army. But it is different for the Xiongnu tribe. They have lived on aquatic plants since ancient times and are familiar with grassland climate and geography. These are the blind spots of the Han army. What's more, the Huns are a nation that grew up on horseback. They are not only good at raising horses, but also proficient in riding and making weapons. These are the great advantages of grassland operations, which the Han army does not have.

As the saying goes, defensive warfare is of course much easier than invasive warfare. If we let Yanzhao's army go deep, they will certainly get no benefit. Therefore, it is not that the Han Dynasty was weaker than Yanzhao in the Warring States period, but that the purpose of the war was different.

Another important reason is that the Huns in the Warring States period are different from those in the Han Dynasty. The Xiongnu in the pre-Qin period was just a loose tribal alliance, with internal and external troubles and many contradictions. However, since Maodun became Xiongnu Khan, he has been expanding Xiongnu tribes by force, and he has conquered and conquered many small and medium-sized tribes. It also wiped out Donghu in one fell swoop, making Donghu a part of the Xiongnu tribe, and the Xiongnu became very powerful. According to historical records, the Huns even had hundreds of thousands of soldiers who controlled the strings. The main forces of the Han dynasty add up to only a few hundred thousand military forces, and the strength of both sides has reached a relatively close level. If you face such a powerful grassland regime, will Zhao save effort? I'm afraid the national strength of Zhao Yan and Zhao Can add up to tens of thousands of cavalry.