In the early years of Emperor Wu of Han's reign, during a battle with the Xiongnu, many prisoners were captured. From their confessions, the emperor learned of a nomadic people called the Great Yuezhi, who lived near Dunhuang and the Qilian Mountains. The Xiongnu and the Great Yuezhi had clashed over territory, with the Yuezhi suffering repeated defeats. The Xiongnu leader, Laoshang Chanyu, killed the Yuezhi king and turned his skull into a drinking cup. After several wars, the Yuezhi's power waned and their population dwindled, forcing them to migrate westward to escape the Xiongnu, while also seeking revenge. Realizing that the Han could ally with the Yuezhi against the Xiongnu, Emperor Wu issued a nationwide call for talented individuals willing to embark on a diplomatic mission to the Western Regions.
At this time, a man named Zhang Qian volunteered to go on a mission to the Western Regions. Emperor Wu of Han greatly admired his courage and ordered him to lead a group of one hundred people on this diplomatic journey. A surrendered Hu (non-Han) person who had submitted to the Han Dynasty, named Tangyifu, was appointed as the guide by Emperor Wu because he understood some of the languages of the Western Regions and was familiar with the routes, so he set out together with Zhang Qian.
In 139 BCE, Zhang Qian and his party set out from Longxi (present-day Lintao, Gansu) and headed westward, arriving at the Hexi Corridor. After the Greater Yuezhi migrated away from this area, it became territory of the Xiongnu. Zhang Qian, worried about encountering Xiongnu, eagerly hoped to quickly pass through the Hexi Corridor, but unexpectedly, Xiongnu cavalry spotted them, and the entire party was captured and taken to the Xiongnu royal court (near present-day Hohhot, Inner Mongolia), where they met the Chanyu Junchen.
Junchen Chanyu certainly would not allow Zhang Qian to go to the Greater Yuezhi; he knew the Han Dynasty wanted to ally with the Greater Yuezhi to attack the Xiongnu, and now that he had captured the Han envoy, Junchen Chanyu decided to place them under house arrest. To reach the Greater Yuezhi, one had to pass through Xiongnu territory, so no matter which envoy the Han Dynasty sent to the Western Regions in the future, they would be intercepted by the Xiongnu. It was precisely because Junchen Chanyu had calculated this that he dared to arrogantly imprison Zhang Qian.
In order to discourage Zhang Qian from carrying out his mission to the Western Regions and to make him stay in Xiongnu wholeheartedly, the Chanyu Junchen came up with many ways to retain Zhang Qian, even finding a Xiongnu woman to be his wife, with whom he had children. On the surface, Zhang Qian complied with the Xiongnu, but in his heart he never forgot the task assigned to him by Emperor Wu of Han—he was determined to reach the Yuezhi. Zhang Qian lived cautiously among the Xiongnu tribes, instructing the other envoys to pretend to accept the Xiongnu's various arrangements while secretly looking for an opportunity to escape.
By 129 BCE, Zhang Qian had lived among the Xiongnu for a full decade. Seeing that Zhang Qian and his companions showed no signs of resistance, the Xiongnu gradually let their guard down, and the Chanyu believed that Zhang Qian had abandoned any intention of reaching the Dayuezhi, content to live quietly in the desert. One day, seizing an opportunity when Xiongnu vigilance was lax, Zhang Qian led his envoys without hesitation in an escape from the Xiongnu court. Thanks to ten years of daily interaction with the Xiongnu, the Han envoys had more or less learned the Xiongnu language, and since they continued to wear Xiongnu clothing, they went unnoticed along the way. Moreover, Zhang Qian had already familiarized himself with the routes to the Western Regions, so this time they managed to flee Xiongnu territory without much delay.
After escaping, Zhang Qian learned that conflicts had broken out among the Western Regions states; the Greater Yuezhi, harassed by the Wusun (in the present-day Ili River valley) and the Xiongnu, had migrated further west and settled in the former territory of the Daxia kingdom. The Greater Yuezhi was now even more distant, and Zhang Qian and his men did not have enough food and water to sustain such a long journey, so Zhang Qian decided to first head southwest to Dayuan and request assistance from the king of Dayuan.
The group traveled westward along the Tarim River, passing through Kuqa and Kashgar, then crossed the Pamir Mountains, finally arriving in Dayuan (present-day Fergana Valley in Uzbekistan) after more than ten days. Along the way, many envoys lost their lives due to the harsh conditions of the desert and wilderness, but fortunately, Tangyifu was skilled at hunting wild birds and animals, which prevented the entire party from perishing.
Upon learning of Zhang Qian and his companions' experiences, the King of Dayuan expressed willingness to escort them to the Yuezhi. Zhang Qian was delighted and promised that upon returning to the Han Dynasty, he would report to Emperor Wu of Han and present gifts and jewels in return. The King of Dayuan had long heard that the Han Dynasty was a prosperous and powerful state and was eager to establish friendly relations, but the Xiongnu blocked the way, preventing contact. Zhang Qian's words reassured the King of Dayuan. Before long, the Kingdom of Dayuan sent several attendants and interpreters to accompany Zhang Qian to Kangju (in present-day Uzbekistan and Tajikistan), where the King of Kangju then arranged for them to be taken to the Greater Yuezhi.
After Zhang Qian presented Emperor Wu of Han's proposal to the people of the Dayuezhi, he was outright rejected. It turned out that the place where the Dayuezhi had settled had lush grasslands and abundant resources, far from both the Wusun and the Xiongnu. Their peaceful life made the Dayuezhi forget the pain of war, and they had no desire to lose their territory again. Moreover, the Han Dynasty and the Dayuezhi were separated by a great distance—the Xiongnu could attack at any time, while Han troops would take a long time to arrive. Unwilling to give up, Zhang Qian stayed with the Dayuezhi, trying to persuade their king. A year passed in the blink of an eye, but the Dayuezhi king never agreed to an alliance with the Han. Left with no choice, Zhang Qian set out on his journey back to the court, carrying his regrets.
In 128 BCE, Zhang Qian departed from the Greater Yuezhi and began his journey back to the Han Dynasty. To avoid being captured again by the Xiongnu, Zhang Qian decided to cross through the southern part of the Tarim Basin, passing through Shache, Yutian (present-day Hotan), and Shanshan (present-day Ruoqiang), before arriving in the territory of the Qiang people. Believing that this time he would surely return safely, he was caught off guard when he discovered that the Qiang's lands had also been occupied by the Xiongnu. Xiongnu cavalry seized Zhang Qian and several of his envoys, and they were detained for another year.
In 126 BCE, internal conflict broke out among the Xiongnu when the Chanyu Junchen died, leading to a struggle between his younger brother, the Left Luli King Yizhixie, and the crown prince Yudan; Zhang Qian seized this opportunity to escape with his Xiongnu wife, children, and his attendant Tangyifu, and this time, they finally made it back to the Han Dynasty.
Zhang Qian's mission to the Western Regions lasted a total of thirteen years; he set out with over a hundred men, but only Zhang Qian and Tangyifu returned, having endured countless harsh environments along the way and even imprisonment by the Xiongnu—how could others truly comprehend the suffering he experienced? Although Zhang Qian did not accomplish the task assigned by Emperor Wu of Han, his journey had a profound impact on both the Western Regions and the Han Dynasty. Since ancient times, many ethnic groups had lived in the Western Regions, but due to the great distance, they had never established contact with the Central Plains. Zhang Qian's first mission to the Western Regions spread knowledge of the Han Dynasty, gradually prompting the various states of the Western Regions to begin interacting with the Central Plains. After returning to court, Zhang Qian provided Emperor Wu with a detailed account of the locations, local products, cities, and routes of the Western Regions, which laid the foundation for the later development of the Silk Road and also constituted the first detailed record of the geography and features of the Western Regions.
Emperor Wu of Han, upon learning of the Western Regions from Zhang Qian, appointed him as Grand Palace Grandee and Tangyifu as Envoy Marquis, granting them many rewards.
While in the land of the Great Yuezhi, Zhang Qian once visited the kingdom of Daxia (Bactria), where he learned that there was a route southwest of Shu Commandery leading to Shendu (present-day India), and continuing further would reach Daxia. Zhang Qian then submitted a memorial to Emperor Wu of Han, expressing his willingness to open up this southwestern barbarian route. Emperor Wu granted him a large number of men and horses, and Zhang Qian divided them into four groups, each setting out toward Shendu. When they reached Kunming, the local people stopped Zhang Qian and absolutely refused to let him pass through their territory. No matter how Zhang Qian explained, the locals would not allow him to proceed, so Zhang Qian had no choice but to return to Chang'an. Although he did not open a new route to the Western Regions, Zhang Qian gathered considerable information about local customs and conditions along the way, which was still a meaningful achievement.
Later, Zhang Qian followed the Grand General Wei Qing in attacking the Xiongnu, achieved military merits, and was granted the title of Marquis of Bowang; then, together with Li Guang, he campaigned against the Xiongnu again, but was demoted to commoner status for delaying the military schedule.
In 119 BCE, Emperor Wu of the Han Dynasty, seeking to ally with the Wusun to attack the Xiongnu, reappointed Zhang Qian as a General of the Palace Gentlemen and sent him with 300 men on a mission to the Wusun, bringing large quantities of livestock and daily necessities. After arriving in the Wusun territory, Zhang Qian dispatched his attendants to various states such as the Dayuezhi, Dayuan, Kangju, and Daxia, conveying Emperor Wu's desire for friendly relations, and these states all sent envoys back to Chang'an with Zhang Qian.
In 114 BCE, Zhang Qian passed away, and upon hearing this news, the various kingdoms of the Western Regions expressed their deep regret, as the people there held him in great respect; subsequent Han Dynasty envoys thus borrowed the title of Marquis of Bowang to interact with these kingdoms. Zhang Qian's mission to the Western Regions not only opened up the route from the Central Plains to the Western Regions, introducing their specialty products to enrich the lives of the Central Plains people, but also influenced the course of world history.