In ancient times (c. 200 BCE) in China, the nomadic tribes known to the Chinese as the Xiongnu (Hsiungnu) and centuries later known to Europeans as the Huns, were a constant threat to the Han Empire of China. In north central Asia there was a tribal confederation, the Yueh-chih, which had been defeated and driven out by the Xiongnu but threatened revenge against them. The Han Emperor Wu-ti heard of the Yueh-chih and believed they would be valuable allies in his fight against the Xiongnu (Huns). He sent an ambassador, Chang Ch'ien, with one hundred soldiers to make contact with the Yueh-chih. The group had to travel through Hun-occupied territory and were soon captured. The Huns treated the captives fairly well and after ten years Chang Ch'ien and some of his companions escaped. When he met with the Yueh-chih he found that they were not interested in an alliance to fight the formidable Huns. On his way back to China Chang Ch'ien was again captured but due to a civil war among the Huns he was able to escape again after about one year. He returned to Chang-an (present day Xi'an), the capital of the Han Empire, after an absence of thirteen years to report that the alliance that the Emperor hoped for was not possible. But Chang Ch'ien was able to report some more interesting news. While with the Yueh-chih he heard of cities to the west that had things the Emperor might want. These cities were Ferghana, Bokhara, Samarkand. The cities Chang Ch'ien heard may have also included the cities of Persia and possibly of the Roman Empire. In particular Chang Ch'ien told the Emperor of large, powerful horses in the oasis city of Ferghana that would be valuable in battling the Huns.

The Emperor sent several military expeditions to Ferghana to obtain the horses he wanted. But in addition to providing China with a more powerful breed of horses these expeditions opened up a trade route that later became known as the Silk Road.

For more on the history of China see China.