Emperor Taizong of Tang (Chinese: 唐太宗; pinyin: Táng Tàizōng; Wade–Giles: T’ang T’ai-tsung) (23 January 599 – 10 July 649), personal name Li Shimin (Chinese: 李世民), was the second emperor of the Tang Dynasty of China, ruling from 626 to 649. As he encouraged his father, Li Yuan (later Emperor Gaozu) to rise against Sui Dynasty rule at Taiyuan in 617 and subsequently defeated several of his most important rivals, he was ceremonially regarded as a co-founder of the dynasty along with Emperor Gaozu.
He is typically considered one of the greatest, if not the greatest, emperor in Chinese history. Throughout the rest of Chinese history, Emperor Taizong’s reign was regarded as the exemplary model against which all other emperors were measured, and his “Reign of Zhenguan” was considered a golden age of Chinese history and required study for future crown princes. During his reign, Tang China flourished economically and militarily. For more than a century after his death, Tang China enjoyed peace and prosperity. During Taizong’s reign, Tang was the largest and the strongest nation in the world. It covered most of the territory of present-day China, Vietnam, Mongolia and much of Central Asiaas far as eastern Kazakhstan. It laid the foundation for Xuanzong’s reign, which is considered Tang China’s greatest era.
In 630, Emperor Taizong sent his general Li Jing against Eastern Tujue (proto Turks)– to which Tang had once submitted—defeating and capturing its Jiali Khan Ashina Duobi and destroying Eastern Tujue power. This made Tang the dominant power in East and Central Asia, and Emperor Taizong subsequently took the title of Tian Kehan (“Heavenly Khan”).
Unlike many of the nobility of the time, Emperor Taizong was a frank rationalist, openly scorning superstitions and claims of signs from the heavens. He also modified important rites in order to ease the burden of agricultural labour.The modern Chinese historian Bo Yang opined that Emperor Taizong achieved greatness by enduring criticism which others would find difficult to accept whilst trying hard not to abuse his absolute power (using Emperor Yang of Sui as a negative example), as well as through his employment of capable chancellors such as Fang Xuanling, Du Ruhui and Wei Zheng. Emperor Taizong’s wife Empress Zhangsun also proved to be a capable assistant.