During the early period of the Tang Dynasty (618-907), Baekje (18 BC-AD 660) and Goguryeo (37 BC-AD 668) of the Korean Peninsula became tributary states of China due to wars. Later, Silla unified the Korean Peninsula, and developed diplomatic relations with China, which designated Chang'an (current day Xi’an in Northwest China's province) as its capital.
Chang'an and the Korea Peninsula kept close contact due to the convenient water and land transports, which were issued by Jia Dan (730-805), a famous politician and geographer of the middle Tang Dynasty.
During that time, the diplomatic model between two sides was that of a tributary relationship. States of the Korean Peninsula frequently presented gifts to the royal court to showcase their faithfulness. The number of tribute from the three states greatly increased from before.
According to the record, Silla dispatched envoys to Chang'an 117 times during the 240 years from the unification of the Korean Peninsula to the end of the Tang Dynasty.
Even when Emperor Xuanzong of the Tang Dynasty moved to Chengdu, Sichuan province during the An Lushan Rebellion, Silla still sent envoys to present the tribute, which touched the emperor greatly.
The trade between both sides greatly developed during the Tang Dynasty. Businessmen from Silla brought calculus bovis, ginseng, sealskin, gold, and silver to China, which ranked as among the top imports of that time, and enriched the lives of Chinese people. Meanwhile, they brought back silk, porcelain, tea, and books, changing the quality of life in Silla.
Silla also dispatched overseas students, monks, and members of the royal family to enhance political, economic, and cultural exchanges with Chang’an. According to records, Silla had the most overseas students in China during the Tang Dynasty.
In 840, the number of students who returned to Silla after finishing their studies once reached more than 100. From 821 to the end of the Tang Dynasty, about 58 Silla students passed the imperial examinations of the dynasty, and some served as government officials at the Tang royal court.
Silla was greatly influenced by the Tang Dynasty in most social aspects. From 639 to 749, Silla designated special people to study the Tang's achievements in medicine, astronomy, and clepsydra. It then took Tang Dynasty's administrative structure as an example to set up its own posts. In 675, Silla officially applied the calendar of the Tang Dynasty.
In 788, Silla started to select government officials through imperial examinations. The etiquette and law systems in Silla were also revised according to those of the Tang Dynasty.
In the middle of the seventh century, Xue Cong, a Silla scholar, created a new way of phonetic notation to mark the auxiliary words in Korean with Chinese characters, promoting cultural popularization and development.
In 828, tea was introduced to Silla and Korean people started to plant tea. Block printing was also introduced to Silla during the end of the Tang Dynasty.
During the long-term diplomatic relations, Korean culture had a deep impact on Chang’an. Korean music was popular among Chinese and the Korean musicians made contributions to the cultural exchanges between China and the Korean Peninsula. The imports from Silla enriched the lives of Chinese people, especially Chang'an residents.