Tang dynasty
Wu Zetian's usurpation

Although she entered Emperor Gaozong 's court as the lowly consort, Wu Zetian rose to the highest seat of power in 690, establishing the short-lived Wu Zhou. Empress Wu's rise to power was achieved through cruel and calculating tactics: a popular conspiracy theory stated that she killed her own baby girl and blamed it on Gaozong's empress so that the empress would be demoted. Emperor Gaozong suffered a stroke in 655, and Wu began to make many of his court decisions for him, discussing affairs of state with his councilors, who took orders from her while she sat behind a screen. When Empress Wu's eldest son, the crown prince, began to assert his authority and advocate policies opposed by Empress Wu, he suddenly died in 675. Many suspected he was poisoned by Empress Wu. Although the next heir apparent kept a lower profile, in 680 he was accused by Wu of plotting a rebellion. He was then banished and later obliged to commit suicide.

In 683, Emperor Gaozong died. He was succeeded by Emperor Zhongzong, his eldest surviving son by Wu. Zhongzong tried to appoint his wife's father as chancellor: after only six weeks on the throne, he was deposed by Empress Wu in favor of his younger brother, Emperor Ruizong. This provoked a group of Tang princes to rebel in 684. Wu's armies suppressed them within two months. She proclaimed the Tianshou era of Wu Zhou on October 16, 690, and three days later demoted Emperor Ruizong to crown prince. He was also forced to give up his father's surname Li in favor of the Empress Wu. She then ruled as China's only empress regnant.

A palace coup on February 20, 705, forced Empress Wu to yield her position on February 22. The next day, her son Zhongzong was restored to power; the Tang was formally restored on March 3. She died soon after. To legitimize her rule, she circulated a document known as the Great Cloud Sutra, which predicted that a reincarnation of the Maitreya Buddha would be a female monarch who would dispel illness, worry, and disaster from the world. She even introduced numerous revised written characters to the language, though they reverted to the original forms after her death. Arguably the most important part of her legacy was diminishing the hegemony of the Northwestern aristocracy, allowing people from other clans and regions of China to become more represented in Chinese politics and government.
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