China, a History

The Silk Road was the most important pre-modern Eurasian trade route. During this period of the Pax Sinica, the Silk Road reached its golden age, whereby Persian and Sogdian merchants benefited from the commerce between East and West. At the same time, the Chinese empire welcomed foreign cultures, making the Tang capital the most cosmopolitan area in the world. In addition, the maritime port city of Guangzhou in the south was also a home to many foreign merchants and travelers from abroad.

Although the Silk Road from China to the West was initially formulated during the reign of Emperor Wu of Han (141–87 BC) centuries before, it was reopened by the Tang in 639 when Hou Junji conquered the West, and remained open for three decades. It was closed after the Tibetans captured it, largely blocking the route to the west. About 20 years later, during Empress Wu Zetian's period, the Silk Road reopened when the Tang empire reconquered the Four Garrisons of Anxi, once again connecting China directly to the West for land-based trade. After the An Shi Rebellion ended in 763, the Tang Empire had once again lost control over many of its outer western lands, as the Tibetan Empire largely cut off China's direct access to the Silk Road. It was not until the 840s that Tang China regained its western territories from Tibet, which contained crucial grazing areas and pastures for raising horses that the Tang Dynasty desperately needed.

Despite the many western travelers coming into China to live and trade, many travelers, mainly religious monks, recorded the strict border laws that the Chinese enforced. As the monk Xuanzang and many other monk travelers attested to, there were many Chinese government checkpoints along the Silk Road that examined travel permits into the Tang Empire. Furthermore, banditry was a problem along the checkpoints and oasis towns, as Xuanzang also recorded that his group of travelers were assaulted by bandits on multiple occasions.