2. The demise of the Western Han Dynasty: In 6 AD, Wang Mang changed the year number to the first year of Jushe. In March, Wang Mang appointed Liu Ying, who was only two years old, as the Crown Prince in order to follow the example of Duke Zhou's regency and prepare for the Han Dynasty. In the following years, the image of Wang Mang claiming to be the emperor on behalf of the Han Dynasty appeared frequently. In the eighth year of AD (the third year), Zitong people mourned the seal and made bronze caskets, which contained "The Seal of the Golden Chamber" and "The Letter from Chi Di Seal to the Yellow Emperor Jin Ce", which made Wang Mang proclaimed himself emperor under the pretext of the death of Emperor Gaozu. So Wang Mang went to the temple to get the bronze casket, then put on the crown to see the Empress Dowager, sat in the front hall of Weiyang Palace, the throne of the emperor, and named the country "Xin". At this point, with the demise of the Western Han Dynasty, Wang Mang realized his political ambition of reforming the ancient system and usurping Han independence.
3. The demise of the Eastern Han Dynasty: during the reign of Huan Ling, he was dissolute and extorted official titles, and farmers could not bear multiple cruel oppression. Finally, the Yellow Scarf Uprising broke out in 184, and the imperial court ordered the states and counties to recruit soldiers themselves, which basically suppressed this massive civil rebellion. In A.D. 190, Dong Zhuo's rebellion broke out again. Since then, the power of the Han court has been sidelined, and the local strongmen have supported their troops with self-respect, which has opened the prelude to the warlord melee in the late Eastern Han Dynasty, and the Eastern Han government existed in name only. In 220 AD, Cao Pi usurped the Han Dynasty and the Eastern Han Dynasty perished.