Taizong was the second emperor of the Tang dynasty. His personal name was Li Shimin. As the second son of Li Yuan, Emperor Gaozu of Tang dynasty, he played a prominent role in toppling the Sui regime and uniting China. In recognition of his contributions, he was made Prince of Qin after his father founded the Tang dynasty. During a military coup known as the Xuanwu Gate Incident on 2 July 626, Li Shimin and his followers killed his brothers Li Jiancheng (the crown prince) and Li Yuanji, and forced his father to abdicate in his favor. One year later, he changed the title of his reign to “Zhenguan.” With a successful carrot-and-stick approach, the new emperor won the submission of the ethnic tribes in the border areas. His troops defeated the militant East Tujue tribe and captured their khan Illig Qaghan in 630, quelled the rebellious Tuyuhun tribe and caught their ruler Murong Fuyun in 635, and conquered the hostile Khocho State in 640, who acknowledged the emperor as their Great Khan. In 641, the emperor secured a marriage alliance with the once-recalcitrant Tibetans by sending Princess Wencheng to marry their leader, Songtsan Gampo. More notably, he took a series of measures to reduce taxes and corvee, lighten penalties, and enforce political and military reforms, ushering in a period of remarkable social stability and economic growth known as the “Prosperity of the Zhenguan Era.” After death, he was buried at the Zhao Mausoleum and given the posthumous title Emperor Taizong of Tang. Due to his rarely-paralleled achievements, he was honored as one of the most influential persons in history of the world, along with Zhu Xi (a prominent Confucian scholar), Liu Che (Emperor Wu of Han), Liu Bang (Emperor Gaozu of Han), and Sun Yat-sen, by Michael H. Hart, a renowned American scholar.