Inventions
The Han rule marked several inventions that were to revolutionize the world: the use of paper, and porcelain which proved valuable for trading and for domestic use. The peak of the Han empire, though, was the employment of military. To ensure the safety of the empire the Han expanded westward to the very rim of the Tarim Basin. This provided for safe caravan travel from China all the way to Rome. This trade path became known as the "Silk Road". To assure peace with the non-Chinese people along the route, a mutual system of tribute was established. The non-Chinese people symbolically acknowledged that the Chinese were superior and paid them tribute; the Chinese in return gave them gifts and ties which strengthened the culture by inter-marriages of the ruling class. The success of the Han kept their dynasty going for nearly four hundred years. With a growing population, increased wealth, and huge numbers of allies (and enemies), the Han lost control of their society. The dynasty collapsed in 220 AD. This period was called the Period of Disunity.
http://library.thinkquest.org/16325/c-han.html