Emperor Taizong, Li Shimin, enjoys a prestige which is quite high. When he was young, he assisted his father in establishing Tang Dynasty. Very talented as a general in war, he wisely employed capable persons to assist him in governing the country. He named the period of his reign "Zhenguan" (627 - 649). Drawing lessons from the downfall of Sui Dynasty, Emperor Taizong carried out many enlightened policies and measures beneficial to the country and people, which consolidated the state power of Tang Dynasty, restored social stablity and boosted the economy. Therefore, the reign was termed "Benign Administration of the Zhenguan Reign Period" by historians.

Emperor Taizong knew that a well-ordered administration needed capable people and a wide range of expert opinions. So he made good use of capable people no matter what their backgrounds were. He once said that using a bronze mirror, one could tidy one's clothes; using history as a mirror, one could know the way of governing a country; using people as a mirror, one could tell right from wrong.

Emperor Taizong implemented many measures that enjoyed the support of people, such as joining countries and prefectures together to reduce expenditure; letting farmer have a certain amount of land and reducing the burden of corvee labor to ensure that farmer had time to work on their land. Citing an ancient saying, Emperor Taizong said that the emperor was like a boat and people were like water; water could carry the boat, but it could also capsize it.

Emperor Taizong won the support of all the minority people by adopting relatively enlightened policies toward them. The ethnic groups in the north called him "Great Khan". The emperor sent Princess Wencheng to the king of Tubo, in Tibet, which made the relations between Han and Tibetan people closer, and contributed to the stablity of China as a multi-ethnic country.