(1) Studying Abroad and Activities of the Remaining People

Overseas activities of the Korean people developed more during the period of Unified Shilla and Parhae than during any other traditional period.
Shilla and Parhae sent many of their students to Tang to import its culture.
The Tang and Shilla governments paid for the educational expenses of many of the students who came from Shilla. These foreign students were called "boarding-students" and could stay in Tang for 10 years in order to finish their studies. There are many students who passed the civil service examination of Tang. Shilla's Kim Un-gyong, Kim Ka-gi, Ch'oe Ch'i-won, Ch'oe Sin-ji, and Parhae's Ko Won-ko, Oh Kwangch'an were among such students. Some of them became Tang officials.
High monks such as Uisang and Wonch'uk also studied in Tang. Upon returning home, Uisang founded the Hwaom-jong (Avatamsaka) in Shilla, and Wonch'uk rose to fame as a high monk in Tang. Hyech'o made a pilgrimage to India and documented his travels in a report called "A Journey to Wang'o ch'onch'uk-kuk" which told of his adventures. This journal became an important document in historical studies of India and Soyok.
On the other hand, after the destruction of Paekche and Koguryo, some of their remain people remained active in China.
Hukch'i sangji, the general who led the Paekche restoration movement also led the Tang army in an expedition against Tufan and Tujue. Ko Son-chi, a Koguryo descendent, became known as a famous general when the Tang army traveled over the Pamir Plateau known as the "Roof of the World" in an expedition to Soyok.

(2) Sea Trade and Chang Po-go

As relations between Shilla and Tang became closer, the two countries' sea trade increased. Shilla exported silk fabric, ramie fabric, ginseng, and gold and silver items and imported silk, books and medicine from Tang.
Many Shilla people frequented Tang to engage in trade. As a result, people of Shilla settled in villages known as "Shilla-bang" around Shandong and the lower Yangzi River, and a supervisory agency known as "Shilla-so" and a Shilla people's temple like "Shilla-won" were established as well. Japanese monks traveling in China frequently visited these Shilla-wons.
As Shilla's sea trade activities increased, pirates became rampant, harrassing sea traders. Chang Po-go, who served th the Tang navy for a time, came back home to establish the Ch'onghae-jin and develop the Shilla naval force. He protected the trade activities of Shilla sailors with convoys to oversee the three seas around the Korean peninsula and the Eastern Sea of China. He became a leader of maritime and trading activities. Being recognized for his merits he was appointed Ambassador to Ch'onghae-jin, but afterwards, as a result of his involvement in political disputes, he suffered a tragic death.

(3) Propagation of Shilla Culture to Japan

After Shilla's unification, diplomatic relations with Japan, which were once severed, were restored and envoys made frequent visits back and forth between the two countries. In the 8th century alone Japanese envoys transporting students and monks to Shilla made eleven different trips.
After returning home, these students played a large role in formulating the legal system of Japan. The Hakuho culture of Japan received a great deal of influence from Shilla culture.
The people of Shilla contributed greatly to the development of Japanese Buddhism during the Nara period. Both Kyoki and Kimi Maro were involved in erecting the great Buddha in Nara.
However, as political confusion worsened in Shilla, diplomatic relations between Shilla and Japan were cut off.