Zhang Qian (; d. 113 BCE), was a Chinese explorer and imperial envoy in the 2nd century BCE, during the time of the Han Dynasty. He was the first official diplomat to bring back reliable information about Central Asia to the Chinese imperial court, then under Emperor Wu of Han, and played an important pioneering role in the Chinese colonisation and conquest of the region now known as Xinjiang. Zhang Qian's accounts of his explorations of Central Asia are detailed in the Early Han historical chronicles ("Shiji", or "Records of the Great Historian"), compiled by Sima Qian in the 1st century BCE .

Zhang Qian was born in present day Hanzhong, Shaanxi, at the border of northeastern Sichuan. He entered the capital, Chang'an, today's Xi'an, between 140 BCE and 134 BCE as a Gentleman (郎), serving Emperor Wu. At the time the Xiongnu tribes controlled modern Inner Mongolia and dominated much of modern Xiyu (西域 "Western Regions").

The Han court despatched Zhang Qian to the Western Regions in 138 BCE with a delegation of over one hundred members, including a surrendered Xiongnu guide. The objective of Zhang Qian's first mission was to seek a military alliance with the Greater Yuezhi (月氏), in modern Tajikistan. On route he was captured by the Xiongnu and detained for ten years. There he married a Xiongnu wife and gained the trust of the Xiongnu leader.

When Zhang finally made it to Yuezhi lands, he found that they were too settled to want war against the Xiongnu. He spent about one year in Yuezhi and Bactrian territory, documenting their cultures, lifestyles and economy, before returning to China.

Zhang Qian starts with a report on the first country he visited (after his captivity among the Xiongnu), Dayuan, in Ferghana, west of the Tarim Basin. They are considered by him as sophisticated urban dwellers, on the same footing as the Parthian and the Bactrians. The name Dayuan (meaning Great Yuan), may be a transliteration of the word Yona used to designate Greeks, who occupied the region from the 4th to the 2nd century BCE.

"Dayuan lies southwest of the territory of the Xiongnu, some 10,000 li (5,000 kilometers) directly west of China. The people are settled on the land, plowing the fields and growing rice and wheat. They also make wine out of grapes. The people live in houses in fortified cities, there being some seventy or more cities of various sizes in the region. The population numbers several hundred thousand" (Shiji, 123, Zhang Qian quote, trans. Burton Watson).

Following Zhang Qian' embassy and report, commercial relations between China and Central as well as Western Asia flourished, as many Chinese missions were sent throughout the end of the 2nd century BCE and the 1st century BCE, initiating the development of the Silk Road:

"The largest of these embassies to foreign states numbered several hundred persons, while even the smaller parties included over 100 members... In the course of one year anywhere from five to six to over ten parties would be sent out." (Shiji, trans. Burton Watson).

"When the Han envoy first visited the kingdom of Anxi (Parthia), the king of Anxi dispatched a party of 20,000 horsemen to meet them on the eastern border of the kingdom... When the Han envoys set out again to return to China, the king of Anxi dispatched envoys of his own to accompany them... The emperor was delighted at this." (Shiji, 123, trans. Burton Watson).

"Even the rest of the nations of the world which were not subject to the imperial sway were sensible of its grandeur, and looked with reverence to the Roman people, the great conqueror of nations. Thus even Scythians and Sarmatians sent envoys to seek the friendship of Rome. Nay, the Seres came likewise, and the Indians who dwelt beneath the vertical sun, bringing presents of precious stones and pearls and elephants, but thinking all of less moment than the vastness of the journey which they had undertaken, and which they said had occupied four years. In truth it needed but to look at their complexion to see that they were people of another world than ours." ("Cathey and the way thither", Henry Yule).