China: Emperor Gaozu (Tang Liyuan), 1st ruler of the Tang Dynasty (r. 618-626).

Emperor Gaozu of Tang (566 - June 25, 635), born Li Yuan, courtesy name Shude, was the founder of the Tang Dynasty of China, and the first emperor of this dynasty from 618 to 626. Emperor Gaozu's reign was concentrated on uniting the empire under the Tang. Aided by Li Shimin, whom he created Prince of Qin, he defeated all other contenders. By 628, the Tang Dynasty had succeeded in uniting all of China. On the home front, he recognized the early successes forged by Emperor Wen of Sui and strove to emulate most of Emperor Wen's policies, including the equal distribution of land amongst his people, and he also lowered taxes. He abandoned the harsh system of law established by Emperor Yang of Sui as well as reforming the judicial system. These acts of reform paved the way for the reign of Emperor Taizong, which ultimately pushed the Tang to the height of its power. Emperor Gaozu passed the throne to Li Shimin (Emperor Taizong) in 626 and became Taishang Huang (retired emperor). He died in 635. (Photo by: Pictures From History/Universal Images Group via Getty Images)