There was chaos in the Central Plains at the end of the Western Han Dynasty. Why didn't the Huns take the opportunity to attack back?

From the end of the Western Han Dynasty to the beginning of the Eastern Han Dynasty, the Central Plains was in chaos, but at this time, the Huns did not fight back, because the Huns actually wanted to use this opportunity to expand their sphere of influence. At that time, all the ancient ethnic minorities in China could pose a threat to the Central Plains. These ethnic minorities were divided into northwest and northeast regions.

It can be said that the ethnic minorities who enter the Central Plains are generally from the northeast, while the ethnic minorities in the northwest have less desire to enter the Central Plains. Moreover, the East Asian continent belonged to the hot subtropical and temperate monsoon climate zone at that time, and the precipitation and temperature decreased from the southeast coast to the northwest inland in turn, so the area with less precipitation was mainly animal husbandry.

Generally, the areas with more precipitation are mainly planted, in the northeast. Agriculture, animal husbandry and fishery economy are relatively developed economies. As we all know, the Huns' agricultural economy depends on animal husbandry, and the degree of sinicization is not high. Moreover, their purpose of plundering the Central Plains is to get more materials for themselves and make their lives better.

It was not to occupy the Central Plains, so from the end of the Western Han Dynasty to the beginning of the Eastern Han Dynasty, the climate in East Asia changed greatly, and the planting industry in the Central Plains was strongly affected. Therefore, the animal husbandry in the northern grassland area has also been affected. Drought and locust plague have caused vegetation to wither into the city for thousands of meters, so the economic foundation here is very weak. Moreover, the Huns were strong only because their military strength was overwhelming and their imperial power was not very strong, so they did not enter the Central Plains in those years because their imperial power was not strong.