Historically, Qin Shihuang unified the six countries, unified measurement, and built the Great Wall to prevent foreign invasion. But burning books and burying Confucianism drove the people to revolt. During the reign of Emperor Wu of the Han Dynasty, he fought against Xiongnu, although his martial arts were high. However, in the case of successive victories abroad, he accused himself of internal crimes and failed in his internal affairs. Emperor Taizong unified China militarily, which had a great influence overseas and was honored as Tiankhan by foreign countries. He pioneered the "rule of chastity" in the history of internal affairs and was a rare monarch. He also laid an important foundation for the prosperity of Kaiyuan and pushed the traditional Chinese agricultural society to the peak. Song Zu's word should be Song Taizu Zhao Kuangyin. He is the only emperor in history who opened a century-old dynasty as a professional soldier. It destroyed the separatist regimes of Nanping, Hunan, Houshu, Nanhan and Nantang successively, and strengthened the defense against the northern Khitan. He changed the political structure during the Five Dynasties and Ten Kingdoms period, giving priority to civil servants and weakening the rights of military commanders, thus creating a peaceful and stable Song Dynasty. However, the cause of his death is a great mystery in history, which may be. Genghis Khan, who established one of the best big countries in human history and the strongest legion in the era of cold weapons, did not know how to govern the country, but built the country by burning, killing and looting. The Yuan Dynasty perished quickly and sadly.