In many ways the Han period (206 BCE-220 CE) was one of the most significant eras in Chinese history. It is a period marked by considerable development in political, religious, intellectual and social systems. By its end, the basic patterns of the Chinese imperial system, government, culture and thought had been established, most of which survive into the twentieth century, even into China's communist era. The boundaries maintained by the Han Empire more or less continue to define our geographical conception of China to this day, and the term Han Chinese is still used today in reference to the country's ethnic majority population.

The first Han emperor was Gao Zu (256-195 BCE), a farmer who successfully led a revolt against the Qin dynasty (221-206 BCE) and its repressive emperor, Shi Huang Di. The dynasty was named after the Han river valley, from whence Gao Zu ruled the empire. Unlike the preceding Qin government, which persecuted Confucianism, Gao Zu organized his administration around its principles. The Han Empire was divided into a series of areas governed by bureaucratic officials, whose appointments were largely based upon merit. This system was so successful that the empire throve and expanded its boundaries, extending from Vietnam in the south to Korea in the north, and far into Central Asia in the West. The Han period is sometimes divide the Han into two parts: the Former, or Western, Han (206 BCE-25 CE), with the capital in Chang'an, and the Later, or Eastern, Han (25-220 CE) when the capital was moved east to Luoyang.

The biggest threat to the Han Empire was the confederacy of nomadic peoples known as the Xiongnu (see the section on the Xiongnu for more details). A military commander named Zhang Qian was sent by the Han emperor Wudi on two diplomatic mission, the first around 120 BCE and the second around 117 BCE, in order to locate potential allies against the Xiongnu. In particular the Han desired an alliance with the Yuezhi, nomadic peoples driven out of their territories in southern Mongolia and western China by the Xiongnu during the previous century. Zhang Qian's mission ultimately did not succeed, but his travels took him as far as the Bactrian region, on the far side of the Hindu Kush Mountains. His report was recorded by the Han-era historian Sima Qian, and he is said to have described to the emperor in great detail all that he had encountered in his travels, including the use of horses in the Bactrian cavalry much larger than the Mongolian ponies used by the Xiongnu. The importation of these horses became a high priority to strengthen the Han military, and their successful implementation against the Xiongnu played an important role in the transfer of the western regions of China from Xiongnu to Han control.

Even after a dissolution of the Xiongnu leadership in 54 BCE led to the end of the hostilities, the Chinese demand for Central Asian horses would continue unabated for many centuries. A long succession of Chinese emperors developed what can only be described as a obsession with the spirited and powerful steeds they called a variety of poetic names, including "celestial horses." Horses, of course, were not the only commodity exchanged between the Han and the various Central Asian kingdoms; wine, fruit, nuts, woolen textiles and rugs, fur, jade and semi-precious stones such as lapis lazuli were all brought from beyond the Han military fortifications at Dunhuang and into the empire. In return, Han traders exported worked gold objects, polished mirrors, reams of silk, and other manufactured goods.

Along with all the material exotica that made its way into Han China came other incidental imports, including religion, for it was during this time that Buddhism diffused into China. Diplomatic missions also traveled the trade routes, with the arrival of Roman envoys sent by emperor Marcus Aurelius Antoninus recorded in 166 CE. It seems, however, that the Han court was rather disappointed with the Roman diplomatic offerings of ivory, rhinoceros horn and tortoiseshell, having expected more rare and exotic gifts from such distant lands.