Emperor Taizong of Tang (T?ng T?iz?ng, Wade-Giles: T'ai-Tsung, January 23, 599  July 10, 649), personal name L? Sh?m?n, 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.