Emperor Taizong of Tang, personal name Li Shimin, was the second emperor of the Tang dynasty of China, ruling from 626 to 649. Taizong subsequently played a pivotal role in defeating several of the dynasty's most dangerous opponents and solidifying its rule over China.
Taizong is typically considered to be one of the greatest emperors in China's history and henceforth, his reign became regarded as the exemplary model against which all future emperors were measured. His era, the "Reign of Zhenguan (Chinese: 貞觀之治)" is considered a golden age in ancient Chinese history and was treated as required studying material for future crown princes.
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https://en.wikipedia.org/wiki/Emperor_Taizong_of_Tang