Empress Wang Zhengjun, mother of Emperor Cheng of Han, had eight brothers. The second son of her second brother, Wang Man, was named Wang Mang. Some court ministers praised Wang Mang highly, so Emperor Cheng enfeoffed him as Marquis of Xindu and later appointed him Grand Marshal, granting him control over the imperial court. Wang Mang diligently sought out talented individuals from across the land, and renowned scholars from near and far flocked to join him.
In 7 BC, Emperor Cheng died and a new ruler ascended the throne—Emperor Ai of Han. Emperor Ai honored Wang Zhengjun as Grand Empress Dowager. After Emperor Ai's six-year reign, he also died. Wang Mang then installed a nine-year-old boy, Emperor Ping of Han, and had Grand Empress Dowager Wang Zhengjun act as regent. All state affairs were now decided solely by Wang Mang.
After securing power, Wang Mang's subordinates petitioned the Grand Empress Dowager to further enfeoff him as Duke of Anhan. Wang Mang refused the title and fief, feigned illness, and stayed in bed, refusing to rise. The Grand Empress Dowager then conferred upon Wang Mang the title of Grand Tutor, honored him as Duke of Anhan, and granted him an additional fief of 28,000 households. Wang Mang accepted the title but returned the land grant.
In 2 AD, the Central Plains suffered from severe drought and locust plagues. Yet the imperial court continued to press hard for grain and taxes, causing unrest throughout the empire. To ease the people's resentment toward the court and officials, Wang Mang advised the Grand Empress Dowager to promote frugality in grain and cloth. His own family led by example, adopting a vegetarian diet, and he donated one million coins and 300 hectares of land for disaster relief. Following his lead, some nobles and ministers reluctantly contributed portions of their land and houses. As a result, Wang Mang's reputation grew even greater.
The following year, when Emperor Ping was only twelve, Wang Mang requested the Grand Empress Dowager to arrange a marriage for the young emperor. She selected Wang Mang's daughter and planned to hold the wedding the next year. After making a show of refusing, Wang Mang accepted. Fearing that Emperor Ping's mother's family might interfere in politics, Wang Mang enfeoffed the emperor's mother, Wei Ji, as Queen of Zhongshan and ordered her to remain there, forbidding her from coming to the capital.
After the new year, thirteen-year-old Emperor Ping married and made Wang Mang's daughter his empress, making Wang Mang the imperial father-in-law. The Grand Empress Dowager offered Wang Mang 25,600 hectares of land in Xinye (modern Xinye, Henan), but Wang Mang again declined.
Wang Mang dispatched eight trusted ministers, including Wang Yun (Yùn), to travel across the empire, spreading news of his refusal to accept the Xinye land. Small landowners and peasants, who deeply resented powerful land-grabbing magnates, upon hearing that Wang Mang would not even accept land, praised him as a truly virtuous man. At this time, Liu Qing, Marquis of Quanling, submitted a memorial to the Grand Empress Dowager, saying: "We should restore the ancient precedent of the Zhou Dynasty, when the Duke of Zhou assisted King Cheng. Please allow the Duke of Anhan to exercise the authority of the Son of Heaven."
Thus, Wang Mang "restored antiquity" and became Emperor Ping's regent.The eight men Wang Mang had sent to observe local customs returned, bringing back various ballads praising him. Over 480,000 people—including court ministers, local officials, and commoners—petitioned the Grand Empress Dowager to further honor Wang Mang.
As Wang Mang's prestige rose, Emperor Ping increasingly found him terrifying and hateful, muttering complaints in private. When Wang Mang heard this, he became furious. One day, during a grand gathering where ministers were offering birthday wishes to Emperor Ping, Wang Mang personally presented a cup of poisoned wine. Emperor Ping drank it, fell gravely ill the next day, and died within a few days. Wang Mang then staged a dramatic display of grief.
Emperor Ping died at the age of fourteen, leaving no son. Although Emperor Xuan of Han had many grandsons, Wang Mang deliberately bypassed the older ones and chose Liu Ying, a two-year-old great-grandson (son of a grandson) of Emperor Xuan, installing him as Crown Prince, also known as the "Child Emperor." Wang Mang's daughter was made Empress Dowager. The Han dynasty, founded by Emperor Gaozu, was visibly slipping into Wang Mang's grasp.
Liu Chong, Marquis of Anzhong, rose in opposition. His confidant Zhang Shao helped him gather over a hundred followers and rashly attacked Wan city, defended by several thousand soldiers. In the battle, Liu Chong's forces were quickly defeated, and both Liu Chong and Zhang Shao died in the chaos. Liu Chong's uncle and Zhang Shao's cousins, fearing Wang Mang's retribution, voluntarily went to Chang'an to surrender. To calm public sentiment, Wang Mang pardoned them all.
Ministers again petitioned the Grand Empress Dowager to further expand the Duke of Anhan's authority. Grand Empress Dowager Wang Zhengjun then issued an edict naming Wang Mang "Acting Emperor" (the term "Acting" meaning "regent").
But the following autumn, Zhai Yi (Zhái Yì), the governor of Dong Commandery, rebelled. He allied with several members of the imperial clan, declared Liu Xin emperor, and proclaimed himself "Grand Marshal Pillar-of-Heaven Great General." He called upon the realm: "Wang Mang poisoned Emperor Ping and seeks to seize the Liu family's empire. Now we have an emperor—let all rise up and punish Wang Mang!" By the time Liu Xin and Zhai Yi reached Shanyang Commandery (capital in modern northwest Jinxiang, Shandong), they had already gathered over 100,000 troops.
When the alarm reached Chang'an, Wang Mang, holding the three-year-old Child Emperor in his arms, prayed day and night in the ancestral temple. He announced to the empire that he was merely acting in the emperor's stead and would eventually return power to the Child Emperor. Yet Wang Mang realized that an "Acting Emperor" could not truly govern—why not become a real emperor? At this moment, a group of people began claiming to receive divine commands from Heaven, proclaiming "Wang Mang is the true Son of Heaven." A bronze box inscribed with "Emperor Gaozu of Han cedes the throne to Wang Mang" was also "discovered" in the temple of Emperor Gao.
This time, Wang Mang no longer refused. In the first month of 9 AD, Wang Mang changed the Han dynasty into the Xin dynasty, declared himself the "Xin Emperor," and demoted the Child Emperor to Duke of Ding'an. From Emperor Gaozu to Emperor Ping, the Western Han dynasty, with its twelve emperors and 214 years of rule, thus came to an end.