Wang Mang established the Xin Dynasty for 15 years and claimed to be the emperor. So why did his head be preserved for more than two hundred years after his death?

usurpation of the Han Dynasty Wang Mang
Wang Mang rose in the late Eastern Han Dynasty. As a royal relative, at his highlight moment, he can be said to be a "god". His performance of Hollywood actor level won the recognition and trust of everyone. He is humble, courteous, fair and honest, and his reputation is widely circulated. At that time, everyone in the world believed that following Wang Mang would be able to achieve a well-off life soon. Even the royal family of Liu questioned their ruling ability, believing that Wang Mang was a natural ruler (it was unprecedented), and the people were willing and the general trend was in full swing. Wang Mang took the position of the young Han Ping Wang Ruziying in an open manner under the great situation of returning home, established a new dynasty, ascended the throne of the emperor, and looked down on the world.
Then the situation took a sharp turn, and Wang Mang started a crazy and running wildly on the road to death. He killed his four sons (the remaining two sons were buried with him), making all relatives in danger and stay away from him; the political reforms he carried out almost caused all the nobles to lose some vested interests, and thus hated him to the core; the economic reforms he carried out made the people displaced and the people were living in poverty; every move he took could bring devastating blows to all classes across the country. Looking at the entire history, it can be said that they were unprecedented and no one came later. He boiled the entire country with his own strength. His followers were disloyal, the aristocratic class was ready to move, the people were in a deep and hot manner, and the ethnic minorities on the border were also angered by him one by one, ready to go to war at any time. In addition, natural disasters continued, the huge Green Forest and Red Eyebrow Uprising broke out. In September of the fourth year of Dihuang (23), the Green Forest Army invaded Chang'an, and Wang Mang was killed by the merchant Du Wu , and the Xin Dynasty was destroyed.

The world is in chaos
Wang Mang eventually died tragically. According to " Han Shu·Biography of Wang Mang ", dozens of soldiers cut off his head, dismembered his body, chopped his muscles and bones, cut off his tongue and stir-fried, but they still couldn't help but feel sorry for him. Everyone carried his head on the street with a bamboo pole, and then hung it on the city gate for public display-

Liu Xiu overthrew Wang Mang
Eastern Han After the establishment of the Eastern Han Dynasty, in order to prevent Wang Mang, the evil thief of usurping the Han Dynasty, never turn over, a wise man offered good advice to Emperor Guangwu Liu Xiu, keeping Wang Mang's head, and exhibited it at any time for future generations to watch. It has the effect of shooting three birds with one stone, and demonstrated the victory of the Han family's Liu family. Secondly, it is to intimidate those who dare to rebel in the future. Third, give the royal family members self-warning (if you don’t do it well, this will be the end). Emperor Guangwu Liu Xiu happily adopted this trick, so Wang Mang's head enjoyed anti-corrosion treatment and was retained by the Eastern Han Dynasty, Wei and Jin Dynasty for 227 years, which Wang Mang did not expect.
Conclusion: Virtue is not worthy of position, ability is not worthy of position, and will eventually be abandoned by history and the people!