(1) Political Advances by Paekche

Among the Three Kingdoms, Paekche was the most active in making advances abroad. In the mid-4th century, when Dong-Jin was weakened, Paekche advanced to Liaoxi and Shandong of China, and it also made inroads into many parts of Kyushu, Japan. Through these activities, for a time Paekche formed a large sphere of influence connecting the peninsula with Liaoxi, Shandong and Japan.
However, after the 5th century, with the southward push of Koguryo and Chinese resistence, Paekche's influence was weakened.
The Kingdom of Kaya also, early on, advanced to Japan. In various areas of Japan, the activities of Paekche and Kaya are noticeable and Koguryo also left footprints of their activities in Japan.

(2) Monks' Study and Their Activities in China

After the introduction of Buddhism, many monks of the Three Kingdoms went to China to study, and some even travelled to India. A Koguryo monk named Sungnang grasped the esoteric meanings of Buddhism and trained a large number of students in China to become harbingers of Sanlunzong of China.
Kyomik of Paekche under the reign of King Song traveled to India and brought back Buddhist books and translated them together with other monks.
In Shilla, monks studying abroad were also very fashionable. All of the high monks of Shilla except Wonhyo learned the Buddhist canon in China. Among them, Won'gwang and Chajang, after returning home, contributed greatly to the promotion of important state policies.

(3) Emigration of People of the Three Kingdoms to Japan

The history of ancient Northeastern Asian society, generally speaking, flows from the continent toward the ocean, and from cultural highlands to the lowlands. Riding on this current, during the prehistoric age Korea introduced metal civilization to Japan and taught them rice farming. Upon entering the age of written history, many people journeyed across to the Japanese archipelago. The Japanese called these people Toraijin (those from the Three Kingdoms) and greatly welcomed them for they brought with them advanced skills and cultures to help civilize ancient Japan. As conflicts among the Three Kingdoms intensified and social confusion increased, a considerable number of people emigrated to Japan.
These emigrants resided in groups in the Yamato district in the heart of Japan as an influencial force of the times, taking charge of political and cultural activities in Japan. They displayed their ability to develop underdeveloped areas. The useable wilderness and swamps of Musashino in today's Tokyo are the gifts of immigrant groups from Koguryo under the leadership of Yakkwang (Wakamitsu).

(4) Diffusion of Cultures of the Three Kingdoms to Japan

The cultures which were developed during the Three Kingdoms period were propagated to Japan and greatly influenced the formation and development of ancient Japanese culture. Especially, the Paekche culture influenced the development of the Asuka culture.
Ajikki and Wang In of Paekche taught Chinese characters to the Japanese, and Tan Yang-i and Ko An-mu, among the five-classic scholars, taught Confucianism in Japan. Under the reign of King Song, Norisach'igye was sent to Japan to introduce Buddhism with Buddhist images and sutras. From Paekche, monks, temple-building architects and Buddhist art manufacturers were sent to influence the development of Buddhism and culture in Japan.

Tamjing of Koguryo taught literature and painting in Japan. The fresco in the Golden Hall of Horyuji Temple, of which Japan is proud, is believed to have been painted by him. The Koguryo monk Hyeja and Paekche monk Hyech'ong became the royal tutors of Crown Prince Shotoku and led the spread of Buddhism in Japan.
The frescos in the Takamatsu old tomb best display the relationship between Koguryo and ancient Japan.
Particularly Paekche, among the Three Kingdoms, introduced many kinds of learnings and technology to Japan and became the driving force of the golden age of the Asuka culture.