Emperor Gaozu of Tang (566 – 25 June 635), born Li Yuan, courtesy name Shude, is the founder of the Tang Dynasty of China, and the first emperor of this dynasty from 618 to 626.
Under the Sui dynasty, Li Yuan is the governor in the area of modern-day Shanxi, and is based in Taiyuan.
In 615, Li Yuan is assigned to garrison Longxi, where he gains much experience by dealing with the Göktürks of the north and is able to pacify them.
Li Yuan is also able to gather support from these successes and, with the disintegration of the Sui dynasty in July 617, Li Yuan – urged on by his second son Li Shimin (the eventual Emperor Taizong) – rise in rebellion.
Using the title of "Great Chancellor", Li Yuan installs a puppet child emperor, Emperor Gong, but eventually removes him altogether and established the Tang Dynasty in 618 as Emperor.
His son and successor Li Shimin honors him as Gaozu ("high founder") after his death.
Emperor Gaozu's reign is concentrated on uniting the empire under the Tang.
Aided by Li Shimin, whom he creates the Prince of Qin, he defeats all the other contenders, including Li Gui, Dou Jiande, Wang Shichong, Xue Rengao and Liu Wuzhou.
By 628, the Tang Dynasty has succeeded in uniting all of China.
On the home front, he recognizes the early successes forged by Emperor Wen of Sui and strives to emulate most of Emperor Wen's policies, including the equal distribution of land amongst his people; he also lowers taxes.
He abandons the harsh system of law established by Emperor Yang of Sui as well as reforming the judicial system.
These acts of reform pave the way for the reign of Emperor Taizong, which ultimately pushes Tang to the height of its power.
In 626, Li Shimin, in a dispute with his brothers Li Jiancheng the Crown Prince and Li Yuanji the Prince of Qi, ambushes Li Jiancheng and Li Yuanji at Xuanwu Gate, killing them.
Fearful of what Li Shimin might do next, Emperor Gaozu passes the throne to him and becomes Taishang Huang (retired emperor).
