The Han Dynasty was the second imperial dynasty in the history of China to implement the county system. Because the history of the first imperial dynasty, the Qin dynasty, was too short to leave much experience for the Han dynasty to learn from, so many ruling methods of the Han dynasty needed to be explored by themselves. We can see that the Han Dynasty actually did quite well. Although there were twists and turns, it managed for 400 years and left a rich legacy for later generations. The Han Dynasty, with its pioneering spirit, brilliant martial arts, prosperous culture and technology, marked the vigor and vitality of China's unified dynasty, and his influence touched almost every level of the Han nation, so that today, 2000 years later, we can still feel that we are still related to him by blood, and we can still gain confidence and courage from the Han history. The greatness of the Han Dynasty first lies in his determination of the official ideology necessary to unify the empire. The Qin dynasty only advocated dharma, but because the court was too hasty and fierce, the people were miserable, and the second one died. At the beginning of Han Dynasty, the loss of Qin Dynasty was recognized and ruled by Huang Lao. Under the specific social conditions in the early Han Dynasty, this undoubtedly played a very important role in healing the wounds of war, restoring economic development and consolidating the ruling order. But after a long time, the evil consequences followed: the kingdom was too strong, the merchants were arrogant and lawless, and the central government was weak, so it was difficult to carry out the invasion of the Xiongnu. If these problems continue, it will be difficult to consolidate the situation of reunification at home and form a joint force abroad to defend the country. At this time, Emperor Wu of the Han Dynasty was born. He resolutely "ousted a hundred schools of thought and respected Confucianism alone" and changed "the rule of inaction" into "the rule of promising". The choice of Hanwu not only chose the official ideology for the Han Dynasty, but also chose the official ideology for China in the next two thousand years, which was proved by the later history. A unified dynasty cannot live without a unified official philosophy, otherwise, it is also a right and wrong, and opinions vary. How can we maintain the order of the country? In fact, Confucianism in Hanwu is not Confucianism, but Xunxue, which is a combination of Confucianism and law. On the one hand, it adopts the core of Confucianism's "benevolence and righteousness", on the other hand, it respects the monarch and suppresses ministers with legalists, formulates criminal laws and uses cruel officials. Han Xuan once made it clear that "the Han family is self-contained, and the overlord is mixed." This new Confucianism, which integrates Confucianism and Legalism, not only has the benevolence of Confucianism, but also has the prestige of Legalism, and avoids the extreme side of the two schools, and has become a sharp weapon to cope with the situation. Some people say that the choice of Hanwu stifled the contention of a hundred schools of thought in China, which is the ideological root of China's backwardness in modern times. This statement seems reasonable, but it can't stand scrutiny. World history used to be a unified empire without an official philosophy. Except China, everyone else turned to religious theology. Compared with religious theology, China's choice is much more secularized and his freedom of thought is stifled to a lesser extent. The rise of Europe nearly 500 years ago was due to complicated reasons, not all religious reasons. Besides, what is the relationship between the prosperity of modern Europe and ancient Greece and Rome? Ancient Greece and Rome disappeared in the course of history, but in the ancient civilization, only China dominated. With this article, we have no reason to criticize Emperor Wu of Han Dynasty. It is worth pointing out that although the Han Dynasty established the exclusive position of Confucianism and banned schools of thought and Sima Qian's works from Xuan Di, heresy always existed. At the end of the Western Han Dynasty, Yang Xiong wrote "Fa Yan", which opposed superstition of immortals and astrology. At the beginning of the Eastern Han Dynasty, there was a new theory of Heng Tan, which opposed providence and "the feeling between heaven and man". What's more, Wang Chong wrote Lun Heng, which strongly criticized Confucian classics of religion and theology with his knowledge of natural science at that time. All these fully show that the official philosophy of the Han Dynasty did not imprison freedom of thought as seriously as imagined. The greatness of the Han Dynasty lies in defining the basic territory of China today with his extraordinary martial arts. For more than 300 years from the beginning of Emperor Wu of the Han Dynasty, the powerful Han Dynasty has been in awe of the four barbarians, and it was not until the Three Kingdoms and the Western Jin Dynasty after the demise of the Han Dynasty that they were able to clean up the barbarians they faced. During the "Five Chaos in China", although the Han people lost their absolute superiority over the barbarians, their relative superiority still existed. The Eastern Jin Dynasty and the Southern Dynasties were located in a corner of the east of the Yangtze River, so they could not compete with the north economically, but never lost to the north militarily, which was caused by the lingering wind of the Great Man Wuwei. Emperor Hanwu has unparalleled curiosity, unlimited energy and supreme fighting spirit. He "fought his way out of Dawancheng, leaped over the Wuhuan base, explored the ancient ditch wall, swung across the elder sister field, fell in love with North Korea, and pulled over Yue Yueqi", which not only leveled North Korea, East Vietnam, Fujian Vietnam and South Vietnam, which were separated by the turmoil at the end of Qin Dynasty, but also regained the land of Qin Hetao from Xiongnu, and even included Yunnan-Guizhou, Hexi Corridor and even the western regions for the first time. Hanwu took the initiative to launch many battles against Xiongnu. After the decisive battle between Monan, Hexi and Mobei, the Xiongnu, who suffered from China for a hundred years, was devastated and forced to move westward. During the reign of Emperor Xuandi of Han Dynasty, the Xiongnu disintegrated internally. At first, five khans competed for position, and later it was divided into two parts. Uhaanyehe in the south surrendered to the powerful Han and survived according to Han. Zhi Zhi Khan in the north can only harass the western regions in the Altai Mountain area of Mobei, and dare not go south to herd horses. In the third year of Zhao Jian (the first 36 years), Chen Tangfa served as the vice captain of the Western Regions of Han Dynasty, and went on an expedition to steal branches in Kangju. He was beheaded after being defeated in World War I.. At this point, the military strength of the Han nationality reached its peak. In his memorial to the emperor, Chen Tang issued the strongest voice in the history of the Han nationality: "Those who openly commit crimes against Han Tianwei will be punished far away." Looking back on the greatness of our ancestors, we can't help but have a boiling passion! If this is lofty, when can we hear that the martial arts of the Eastern Han Dynasty are not as good as those of the Western Han Dynasty, and we made a fatal mistake in the national policy of treating foreigners? He allowed the Qiang people to enter the fortress and live in Jincheng area, which made the Qiang people rebel because of the rapid population growth and poor economy in later generations, and became a major disaster in the Han Dynasty. They spent twenty years trying their best to suppress them. He also allowed the Southern Xiongnu to enter Yanmen, Shanggu and Dai Jun. Although there was no trouble in the Han Dynasty, it laid a chaotic order for the "five disorderly flowers" of later generations. However, in the 16th year of Yongping in Ming Dynasty (73 years), the first year of Yongyuan (89 years), the second year of Yongyuan and the third year of Yongyuan, the Eastern Han Dynasty defeated the Xiongnu four times, knocking down more than 200,000 Xiongnu, forcing the rest Xiongnu to move westward and leave the Mongolian plateau forever. Only the Tang Dynasty defeated the Turks in later generations. Ban Gu and others almost managed the Western Regions for the country and controlled the political situation in the Western Regions for decades. These lonely heroes are almost unique in the 5,000-year history of the Han nationality. The greatness of the Han Dynasty also lies in its brilliant humanities and advanced science and technology. Historically, Sima Qian's Historical Records appeared in the Western Han Dynasty, and Ban Gu's Hanshu appeared in the Eastern Han Dynasty. The former initiated the general history of China's biography, while the latter was the first complete dynastic history of China. Sima Qian's history is "a true record, because it is not empty and beautiful, nor does it hide evil", which just liberates history from the rigid thinking of "scaring traitors". Ban Gu's Hanshu is "not passionate, not rebellious, not blasphemous, detailed and stylish". He adopted Sima Qian's style, but he was more rigorous. Both of them have high literary value, and from the literary point of view, they are both representative works of China's prose. The literary works of the Han Dynasty are also very rich, mainly in three forms: Fu, Prose and Yuefu Poetry. Besides Sima Qian and Ban Gu, there are a large number of unknown authors such as Jia Yi, Chao Cuo, Mei Cheng, Sima Xiangru, Dong Fangshuo, Yang Xiong and Zhang Heng. Fu Zhi Bird, Fu Zhi Zi Xu Fu, Seven Unique Poems, Nineteen Ancient Poems, Peacock Flying Southeast, On Qin, On Gui Su Shu, etc. Are masterpieces in the history of China literature. From a scientific point of view, the Han Dynasty was also a great dynasty in the history of China. Paper was invented in Han Dynasty, some basic chemical knowledge was accumulated, and the ironization of farm tools and weapons was completed. China ancient medicine, agronomy, astronomy and mathematics all formed their own unique systems in the Han Dynasty. In medicine, the representative works of Han Dynasty are Shennong's Classic of Materia Medica and Treatise on Febrile Diseases. The former is China's earliest pharmaceutical work; The latter was written by Zhang Zhongjing, and it is still the basic work of TCM therapeutics in China. In agronomy, the representative work of Han Dynasty is Bi Shengshu written by Bi Sheng, the "Lang Yi" in the reign of Emperor Wu of Han Dynasty. The book summarizes six basic links and technical problems of agricultural production, and summarizes the cultivation methods of more than ten kinds of crops such as cereals, wheat and mulberry, which lays the foundation for ancient agricultural books and crop cultivation theories in China. In astronomy, the Han Dynasty completed four calendars, namely taichu calendar, Trinity Calendar, Seasonal Calendar and Dry Calendar. These calendars are becoming more and more perfect, and they have reached high accuracy in determining the various periods and related astronomical constants of the apparent movements of the sun, the moon and the five stars, forming a unique system. The Han Dynasty made remarkable progress in astronomical instruments and records. The most outstanding achievements are Zhang Heng's armillary sphere, accurate records of sunspots, and the earliest records of nova and supernova in the history of China. In arithmetic, the representative work of Han Dynasty is Nine Chapters Arithmetic. This is the oldest existing mathematical work in China. It marks the formation of a mathematical system with its own unique style in ancient China. Nine-chapter arithmetic is far less abstract, logical and systematic than Euclid's, but it is far superior to the ancient Greek mathematical system in solving practical calculation problems by using arithmetic and decimal system. In addition, the Han dynasty was far ahead of the world in surveying and mapping and steelmaking. The topographic map and garrison map unearthed in Mawangdui are quite close to modern maps, and the technologies of steel explosion, steelmaking and decarburization of cast iron in Han Dynasty are also very advanced. The technology of smelting wrought iron with stir-fried steel in Europe is later than that in China 1900 years. Standing in the 2 1 century today, we look back at the Han Dynasty two thousand years ago, which was a vigorous and impassioned era. What an era of innovation and exploration! How many idioms and allusions have been produced here, and how many heroes and beauties make people sad. It is the cornerstone of the Chinese nation that "peaches and plums don't say anything, a bright future emerges", "joining the army with a pen", "lighter than a feather, more important than Mount Tai", "painting the land as a prison, but you can't enter it at last", "Why should Xiongnu stay at home", "Let the wolf live in a professional place", "Xerox Ran Yan", "The Golden House hides the charming" and "The addiction of broken sleeves". Without the great achievements of the Han dynasty, the history of the Han nation would be inferior. Without the development of the Han Dynasty in many aspects, how could East Asian civilization stand proudly for thousands of years?