The best place is your local or university library.
http://www.mnsu.edu/emuseum/prehisto...china/han.htmlThe Han dynasty, after which the members of the ethnic majority in China, the "people of Han," are named, was notable also for its military prowess. The empire expanded westward as far as the rim of the Tarim Basin (in modern Xinjiang-Uyghur Autonomous Region), making possible relatively secure caravan traffic across Central Asia to Antioch, Baghdad, and Alexandria. The paths of caravan traffic are often called the "silk route" () because the route was used to export Chinese silk to the Roman Empire. Chinese armies also invaded and annexed parts of northern Vietnam and northern Korea toward the end of the second century B.C. Han control of peripheral regions was generally insecure, however. To ensure peace with non-Chinese local powers, the Han court developed a mutually beneficial "tributary system" (). Non-Chinese states were allowed to remain autonomous in exchange for symbolic acceptance of Han overlordship. Tributary ties were confirmed and strengthened through intermarriages at the ruling level and periodic exchanges of gifts and goods.
After 200 years, Han rule was interrupted briefly (in A.D. 9-24 by Wang Mang or , a reformer), and then restored for another 200 years. The Han rulers, however, were unable to adjust to what centralization had wrought: a growing population, increasing wealth and resultant financial difficulties and rivalries, and ever-more complex political institutions. Riddled with the corruption characteristic of the dynastic cycle, by A.D. 220 the Han empire collapsed. http://www-chaos.umd.edu/history/imperial.html