The four-century-long Han rule is divided into two periods: the Earlier or Western Han and the Later or Eastern Han. In between these two was the short-lived Hsin Dynasty (AD 9-23).

The Chinese show their pride in Han accomplishments by calling themselves the Han people. Philosophies and institutions that began in the Chou and Ch\'in periods reached maturity under the Han. During Han times, the Chinese distinguished themselves in making scientific discoveries, many of which were not known to Westerners until centuries later. The Chinese were most advanced in astronomy. They invented sundials and water clocks, divided the day equally into ten and then into 12 periods, devised the lunar calendar that continued to be used until 1912, and recorded sunspots regularly. In mathematics, the Chinese were the first to use the place value system, whereby the value of a component of a number is indicated by its placement. Other innovations were of a more practical nature: wheelbarrows, locks to control water levels in streams and canals, and compasses.
The Han Chinese were especially distinguished in the field of art. The famous sculpture of the "Han flying horse" and the carving of the jade burial suit found in Han period tombs are only two superb examples. The technique of making lacquer ware was also highly developed. The Chinese are proudest of the tradition of historical writing that began in the Han period. Ssu-ma Ch\'ien (145?-85? BC) was grand historian (an office that combined the duties of court recorder and astronomer) during the time of Wu Ti. His \'Historical Records\', which took ten years to complete, established the pattern and style followed by subsequent histories. In the Later Han, the historical tradition was continued by the Pan family. Pan Piao, the father, started to bring Ssu-ma Ch\'ien\'s \'Records\' up to date. The work was continued by his son Pan Ku (twin brother of the general Pan Ch\'ao) and was completed by his daughter Pan Chao, China\'s earliest and most famous woman scholar. Unlike Ssu-ma Ch\'ien, the Pan family limited their work to 230 years of the Early Han. This was the first of the dynastic histories, subsequently written for every dynasty. Pan Chao also wrote a highly influential work on the education of women, \'Lessons for Women\'. \'Lessons\' emphasized the "virtues" of women, which restricted women\'s activities. The Confucianism that the Han Dynasty restored differed from the original teachings of Confucius. The leading Han philosophers, Tung Chung-shu and others, used principles derived from the early Chinese philosophy of nature to interpret the ancient texts. The Chinese philosophy of nature explained the workings of the universe by the alternating forces of yin and yang--dark and light--and the five elements: earth, wood, metal, fire, and water. The Han period was marked by a broad eclecticism. Many Han emperors favored Taoism, especially the Taoist idea of immortality.

Earlier (Western) Han (202 BC-AD 9).
The Han Kao Tsu preserved many features of the Ch\'in imperial system, such as the administrative division of the country and the central bureaucracy. But the Han rulers lifted the Ch\'in ban on philosophical and historical writings. Han Kao Tsu called for the services of men of talent, not only to restore the destroyed classics but to serve as officials in the government. From that time, the Chinese Empire was governed by a body of officials theoretically selected on merit. Such a practice has few parallels elsewhere at this early date in human history.
Later (Eastern) Han (AD 23-220).
The new ruler who restored peace and order was a member of the house of Han, the original Liu family. His title was Kuang Wu Ti, "Shining Martial Emperor," from AD 25 to 57. During the Later Han, which lasted another 200 years, a concerted but unsuccessful effort was made to restore the glory of the former Han. The Later Han scored considerable success in recovering lost territories, however. Sent to befriend the tribes on the northwestern frontier in AD 73, a great diplomat-general, Pan Ch\'ao, eventually led an army of 70,000 almost to the borders of eastern Europe. Pan Ch\'ao returned to China in 101 and brought back information about the Roman Empire. The Romans also knew about China, but they thought of it only as the land where