(1) Adjustment of the Political System
Shilla, which unified the Three Kingdoms. readjusted its political and other ruling institutions, thus stablizing both government and society. After unification, the royal powers of the King were strengthened as a result of the unbroken lineage from King Muyol, and the power of aristocrats was weakened. From then on, the powers of the Sijung, who served as executives and who promulgated the King's orders and enforced laws, were greater than the Sangdaedung, who represented the aristocracy. Marching abreast with many social developments, many offices were established, and schools known as Kukhak were set up to teach Confucianism. Local administrative systems were also reorganized. During the reign of King Sinmun, the country was divided into nine provinces, and under each province, counties (Kun and Hyon) were organized. Five cities were stationed as the heads of these localities to make them the hearts of local government and culture. Shilla reorganized and strengthened the military. In the central headquarters, nine Sodangs (king's guards) were stationed, and in the local areas, 10 Chongs were stationed in important locations of the nine provinces.

(2) Aristocrat-centered Economic Life
The economic life of unified Shilla prospered with the aristocrats at its center. The aristocrats received and owned large acreages of land, and also possessed wide meadows in the mountain valleys and islands. They also possessed many slaves and amassed huge wealth through the practice of usury. The wealthy aristocrats who lived in luxurious houses fell into a life of extravagance and pleasure. In this way, the traditionally strong-spirited Shilla people began to decay spiritually.
On the other hand, farmers in the villages and menials, who lived in the special administration districts, Hyang, So, and Pugok, had to led difficult lives because of their heavy indebtedness to either the state or aristocrats. The government investigated the local lands, population, livestock and even the number of standing trees once every three years in order to administer the labor force and production resources.

(3) Social Changes During the Last Stage of Shilla
Shilla, which enjoyed prosperity for about 100 years after the unification, fell into hardship beginning with the latter half of the 8th century. The continuous royal line of King Muyol was broken with King Hyegong as the last of that lineage, and there was a scramble for the crown among the Chin'gol aristocrats. As a result, in the later Shilla years, confusion was prevalent as 20 kings reigned during a 150-year period. In the countryside, Rebellions headed by Kim Hon-ch'ang sprung up to weaken the power of the central government. When the government and society was in a state of confusion as a result of the scramble for the crown among the Chin'gol aristocrats, the local powers of the chieftains and sea captains gathered strength. As a good example, Chang Po-go maintained power over sea trade in the South and Yellow Seas and monopolized trade with both Tang and Japan to became the master of the sea for a time. The local powers indigenous to their area had their independent ambitions, calling themselves city masters or generals. They were the chieftains who played important roles in weakening the royal structure of the Chin'gol government of Shilla. On the other hand, impoverished peasants became either slaves or thieves. During the reign of Queen Chinsong, peasants rose up in rebellion everywhere, and Shilla fell into a swirl of civil wars

(1) The Founding of Parhae and Its Political System
After the destruction of Koguryo, the remaining people in Manchuria rose up in a restoration movement. Tae Cho-yong, a former general of Koguryo, led the remaining people of Koguryo and the Mohe tribe to found a new state in the area of Dongmiaoshan in Dunhuaxian, Jilin calling his country Chin in 698. Later Chin was renamed Parhae. Parhae recovered almost all of the old Koguryo territory and dominated Manchuria, the Maritime Provinces and northern Korea to become a powerful nation. The ruling classes were mostly composed of the people of Koguryo, and the Mohe tribe formed the greater part of its population. Parhae, with a strong consciousness as being the successor of Koguryo, stood in confrontation with Tang and Shilla, and maintained friendly relations with Japan and Tujue in the beginning stages. From the mid-8th century on, under the reign of King Mun, Parhae maintained peaceful relations with Tang and actively exchanged culture and goods. The official institutions of Parhae were modelled after the Tang system, consisting of three councils--Chongdangsong, Sonjosong and Chungdaesong--each with six divisions. This system resembled the Tang structure in form but in terms of operation possessed unique characteristics. Important state affairs were determined at aristocrats' meetings in Chongdangsong. For local administration, the country was divided into five regional capitals, 15 provinces and 62 counties. Governors and magistrates were stationed as local rulers in each province and county.

(2) The Height of Prosperity and the Fall of Parhae
Parhae reached its zenith of prosperity under the reign of King Son in the early 9th century. During that stage Parhae occupied a large territory, reaching out from the Heilong River (Amur) to the north, Yonghung in Hamgyong-namdo to the south, the Maritime Provinces to the east, and Kaiyuan to the west. Parhae imported civilized culture and goods from Tang, and its culture developed so peculiarly that it was referred to as Haedong songguk (a sage country in the east). However, after King Son, an internal dispute arose among the ruling class, and harmony between the governing Koguryo people and the governed Mohe was broken. Parhae's power was weakened. During the same time, the Qidans growing in the west of Parhae gained more power with each day. Parhae was destroyed by the Qidans in 926. Ever since, Manchuria, which had been the center stage for Korea's national activities, has been estranged from Korea's history.

(3) The Culture of Parhae
Parhae imported the Tang culture over the groundwork laid by traditional Koguryo culture to achieve a relatively developed culture. In Sanggyong, the long standing capital of Parhae, an aristocratic culture developed, and it became the center of culture in Manchuria. Parhae had a Chujagam to instruct Confucianism and Chinese literature, and many sons of aristocracy studied abroad in Tang. Thus, Confucianism and Chinese literature were believed to have been considerably developed. On the epitaphs of Princess Chonghyo excavated in 1980 and of Princess Chonghye unearthed earlier, beautiful poems carved in a pairing style can be found. As poets of Parhae, Yang T'ae-sa, Wang Hyo-ryom, Injong and Chongso are especially well-known. They sailed to Japan where they wrote poems which are still read today.

Among many others, "In the Frosty Sky the Moon Shines and the Milky Way is So Much Cleaner," written by Yang T'ae-sa, was highly appreciated for its brilliant style. Buddhism prospered in Parhae and many temples were erected, but today only the building sites remain. As monks rose in social status they performed important roles not only in the field of religion but also in foreign diplomacy. Injong and Chongso were dispatched to Japan as members of the diplomatic corps. Parhae arts possess an overflowing ambitious spirit which is a character prevalent in the works of Koguryo, and in addition they possess a soft refined quality. The Buddhist images and lotus flower designed tiles unearthed in Sanggyong display the peculiarities of Koguryo art. Moreover, the Ondols and many tombs in lateral stone chambers found in Sanggyong prove that Parhae was the successor to the Koguryo culture. The two stone lions excavated from the tomb of Princess Chong-hye are famous for their refinement. The stone lantern in Sanggyong, which is six meters high, is one of these masterpieces of the stone art of Parhae. Tae Kan-chi is also known to be one of the famous painters. In the recently excavated tomb of Princess Chonghyo a fresco of twelve personages, through which the life of the people of ancient Parhae can be seen, was found.

(1) Development of Buddhism
Shilla Buddhism was further developed after unification as seen by the appearance of many different schools, the five kyo (teaching) sects and the 9 mountains (zen school) sects. Thus, Buddhism was widely spread among the populace. The five kyo sects, which researched Buddhist sutras, were founded at the time of the unification of the Three Kingdoms. Among the Buddhist sects, the Hwaom-jong (Avatamsaka sect) founded by Uisang was welcomed by aristocrats and thus developed more rapidly than any of the others. The high monk representative Wonhyo made efforts to combine Buddhist ideologies and widely propagated Chongt'o-jong (Paradise) to popularize Buddhism to the masses. Toward the end of Shilla, Zen (Dhyana) Buddism was in vogue, and nine denominations of Zen Buddhism existed under the protection of the local clan chiefs. As Buddhism bloomed, Buddhist art also developed and a high degree of scholarly research concerning Buddhism took place.

(2) Confucianism and Technology
During the reign of King Sinmun, a school called Kukhak was established and was staffed by scholars and assistants who instructed Confucianism and Chinese literature. Under the reign of King Wonsong, a special section of learning was established which divided students into three classes according to their academic abilities in order to hire government officials. However, this system was not effectively enforced due to the Kolp'um system, which respected family lineage. Immediately after unification, Kang Su and Sol Ch'ong became highly well-known as scholars. Kang Su was an outstanding penman who was able to compose elegant diplomatic letters.
Sol Ch'ong, the son of Wonhyo, redeveloped the writing system of Idu and utilized it to interpret the classics. Under the reign of King Songdok, Kim Tae-mun wrote many books including Hwarang segi, Kosung-jon, and Kyerim chapchon and was instrumental in creating the traditional culture of Shilla, but unfortunately these books do not remain today. As exchanges with Tang were actively promoted, the number of students sailing to Tang increased. On the whole, most of these students were from the 6-t'upum aristocrat families, and upon returning home, they were critical of the Kolp'um system. Ch'oe Ch'i-won was famous in Tang as an apt writer, but, after returning home to Shilla, he became disillusioned by the world of politics and lived a secluded life. His Kyewon p'ilgyong is still read by many today. In Unified Shilla, woodblock printing developed. The Dharani Sutra discovered in the three-story stone pagodas of Pulguksa Temple was printed in the mid-8th century and is believed to be the oldest woodblock printing in the world. Technology in various fields such as astronomy, medicine, and military science also developed. During the last days of Shilla, Toson widely propagated the theory of geomancy. The theory of geomancy weakened the authority of the Shilla government and supported the growth of the power of local clans. In addition, Taoism and the Ideologies of Laotse and Chungtse were also popularized during this same period.

(3) Hyangga Literature
The Hyangga (folk songs) of the Three Kingdoms came into great popularity after the unification. While Chinese literature developed among the aristocracy, Hyangga was widely spread throughout the commoners, and many of them were written especially by monks and Hwarangs. Among Hyangga writers, two monks--Wolmyongsa and Ch'ungdamsa--are particularly famous. Wolmyongsa composed the songs, "Tosol-ga" (Song of Paradise in Tosol Heaven) and "Chemangmae-ga" (Song to a Dead Younger Sister), while Ch'ungdamsa composed the songs "Anmin-ga" (Song of Peace to Folks) and "Ch'an-Kip'arang-ga" (Song of Praise to Kip'arang). "Che-mangmae-ga" was the song sung by Wolmyongsa when he offered a rite for his dead younger sister. Its lyrics are superb examples of hyangga. During the reign of Queen Chinsong, Taegu hwasang compiled a group of Hyangga called "Samdaemok", which has not been handed down to today. All 25 Hyanggas, including 14 Hyanggas in the Samguk yusa, have been handed down and exist today.

(4) Development of the Arts
The arts of Unified Shilla had Buddhist art as its core. Achievements were made in formative art which was responsible for Buddhist images, stone pagodas and Buddhist bells in temples, which possessed the feature of harmonized and symmetrical beauty. The Sokkuram Grotto and Pulguksa Temple constructed with a prayer to the gods by Kim Tae-song in the mid-8th century are representive of the Buddhist art of Shilla. These were made during the height of the Shilla culture. Sokkuram is a man-made cave temple. In the center of the cave is a seated image of Buddha and on the walls around it, images of Buddha, his disciples and many other standing images showed their conception of the Buddhist world. Its arched ceilings bear a great number of beautiful sculptures and its architecture is exquisite. Sokkuram is one of the best representations of Buddhist art in Shilla. Originally, Pulguksa Temple was a huge temple with over 2,000 partitions. During Hideyoshi's invasions between 1592-97 however, the wooden structure burnt down, and the present building which stands today is a reconstruction from the latter part of the Choson period or a more recent restoration.
However, the stone artifacts of Shilla remain and display the high degree of Buddhist art of Shilla. The three-story stone pagodas known as Sokkat'ap and Tabot'ap (Pagodas of multiple treasures) display a refined beauty. These are representative of stone pagodas of Unified Shilla together with the three-story stone pagoda decorated with four lions at Hwhaomsa Temple. The Blue and White Cloud Bridges, the Lotus Flower Bridge and the Seven Treasures Bridge leading to the front entrance of Chahamun and the stone pillars of Pomyongnu to the west of Chahamun are representative of three dimensional beauty. As Buddhist bells, the bronze bell at Sangwonsa and the New Bell of King Songdok are the most famous. In particular, the New Bell of King Songdok is known as the finest Buddhist bell for its magnificent echo and fascinating sculptures of angels and lotus flowers. Among stone lanterns, the Twin Lantern of Popchusa Temple and the lantern in Pulguksa Temple are known for their balance. The sculptures carved on the monument of King Muyol's tomb and the 12 zodiacal signs carved on the monument of Kim Yu-sin's tomb and Kwaerung's (Hanging royal tomb) are examples of exquisite workmanship. In the field of calligraphy, Kim Saeng was unsurpassed and among painters, Kim Ch'ung-ui became famous in Tang.

(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.