After its long golden era, the SINRA society began showing disruptions on the whole due to various discrepancies within the society. Amongst the many causes, the disintegration of the Chingol aristocrats created the most political upheaval. Political chaos started with the Taegong rebellion in the 4th year (786 AD) of Queen (king) Hyekong's rule. 93 Kakgans of the nation fought one another and the chaos lasted three years.

     The underlying cause of the civil war was the resistance of the nobles against absolute royal authority. Eventually, in the latter period of the SINRA dynasty, this led to the alliance of aristocrats against the monarchy. Here, SANGDEADEUNG, in place of Chipsabujungshi, was once again brought to light and struggles amongst aristocrats followed. As a result, in the 150 years of the latter period, 20 kings ascended the throne. Several of them became the victims of the relentless civil wars.

     With the constant unrests of the society, the limitations of the GOLPUMJE became glaringly obvious. Yukdupum intellectuals who were barred from full political activity due to their low social status began to openly criticize the existing system.

     A representative of such intellectuals was CHOECHIWON who proposed some current affairs reforms to Queen Chinsong. These intellectuals knew that government officials in Tang were appointed through state examinations. In time, discontented with their lack of promotions as a result of their low social status, they gradually further themselves from the center of SINRA in society.

2) The Empowerment of the Regional Clans

     Whilst Chingol nobles wrangled in the metropolis, many a regional power gained ground. This power outflow from the metropolis to the provinces is especially evident at the height of this historical period.

     These clans, instead of trying to enter the central political arena, chose to construct their power base through such breakthrough practices as improving international trade. They focused on encouraging civilian trade rather than the conventional tributary trade.

     Military camps manned by private soldiers began to appear. A representative such camps is JANGBOGO, which was based in CHEONGHEAJIN. Those who grew up in or underwent life in such camps, became very clannish and thus, powerful clans were formed. They governed the provinces directly, collecting taxes through government officials they appointed, and called themselves generals or regional commanders based on their great military strength. Vagabonds and former rebels were cajoled into their camps to build up their numbers, and they openly challenged the central government.

     The appearance of powerful regional clans posed extra burdens on the farmers. This is because of double taxation, that is, they had to pay taxes to the clan they belonged to as well as the central government. Because of this increasing burdens of taxes and compulsory labor, farmers began to run away or formed robber gangs of their own. Also, villages under the sole and direct protection of the powerful clans began to appear as well.

     At any rate, farmers' leaving and running away dealt a serious blow to the old order. In addition, some farmers also rose in revolt. The first uprising, led by Wonjong and Aeno, was raised in the Sabulju (Sangju) area (3rd year of JINSEONGYEOWANG, 889). As their rebel army was considerably strong, government troops dared not attack.

     They were followed by such rebel leaders as Yanggil of Pokwon (Wonju), Kihuon of Chuju (Chuksan), Kyonhuon of Wansan (Chonju) and Kungye, who was a follower of Yanggil. In Pangmin to the south of the capital Chokkojik, rebels in red pants, went on a rampage (10th year of JINSEONGYEOWANG, 896).

4) Foundation of The Later Three Kingdoms

     Taking advantage of the chaos, Kyonhuon founded later BAEKJE while Kungye established later GOGURYEO. They resurrected the old BAEKJE and GOGURYEO dynasty and consolidated their power base, thereby forming a triad-power with SINRA. This period is called the later Three Kingdoms era.

     Kyonhuon was from a powerful clan of the SANGJUSI and rendered distinguished services to the defense of the southwest sea. When revolts broke out at various places, he occupied GWANGJU and founded a nation (3rd year of JINSEONGYEOWANG, 889). Under the slogan of "Retaliation for Uija", he crowned himself king and named the country "Later BAEKJE" with Wansanju (Chonju) as his base (3rd year of HYOGONGWANG). Under a military-like system, he fostered his power by forming alliances with local clans. His rule was an absolute monarchy based on the Maytreya belief.

     Kungye was the illegitimate son of King Honwan of SINRA who was expelled to the provinces as a victim of the struggle for political power. Initially he was a monk but later went to serve under Kihuon when troubled times came. He then became a follower of Yanggil who he later overthrew. Kungye founded Later GOGURYEO under the banner of "Reviving GOGURYEO" and based his capital in Gongak (5th year of HYOGONGWANG, 901). Later he changed the name of his country to Majin, transferred its capital to Chonwon and once again renamed the country Taebong.

     Kungye was very distrustful and during his reign executed many of his followers. He became a tyrant and was later expelled by his subordinates. The man elected to replace him as prince was WANGGEON.

     The first king authored a volume of 'Chonggye', 8 volumes of 'Kyebakyoso' and left 'Shiphunyo' to his posterity. These may be said to be his dying wish and his basic government policies. He left in writing what his successors should observe. 2 years after the death of the first king, the 'Wangkyu Rebellion' broke out. This rebellion was suppressed by Wang Shik Yom's military force but indicated how fragile the royal authority was in those days.

     The royal authority was solidified and stabilized with the reforms carried out by GWANGJONG, the 4th king. He enforced a special law on male and female servants (7th year of GWANGJONG, 956). Servants who had originally been law-abiding citizens were released. Also, servants were the material foundation of the clans.

     A state examination system was enforced based on the recommendation of the Chinese, Ssanggi (9th year of GWANGJONG, 958). This meant the founding of a new bureaucracy. This change can be said to be directly linked to the solidification of the royal authority. Official uniforms of all the government officials were also decided (11th year of GWANGJONG, 960).

     GWANGJONG pushed ahead with a series of policies to solidify the royal authority - by calling himself emperor, changing the names of Kaegyong and Sogyong to Hwangdo and Sodo respectively, and establishing the name of his reign. However, with the death of GWANGJONG, those who were appointed by him also lost their power.

     Subsequently, scholars of the Yukdupum faction of SINRA, including CHOESEUNGRO began to play active roles. CHOESEUNGRO wrote a proposal called `28 Articles of Current Affairs' to SEONGJONGWANG. The articles pointed to a centralized aristocracy. Since they were no regional bases, they concentrated on the promotion of government officials. They were also opposed to absolute monarchy.

7) Contention with Kitan and Yojin.

     The 'March North' policy of GORYEO naturally caused much conflict with the Kitan. Kitan's target was Sung, but it neverthless had reasons to feel apprehensive about GORYEO as well. In the 12th year of SEONGJONG (993), the Kitan led by So Son Nyong (the first invasion) attacked. The crisis was resolved through diplomacy by So He and GORYEO acquired 6 provinces of Kangdong. However, in the lst year of WONJONG (1010), the Kitan invaded again blaming the political change caused by Kangjo (the second invasion). HYEONJONG had to take refuge in Naju during the attack. The second invasion bore the Kitans no fruit, however, and they had to withdraw.

     Shortly, Yojin began harassing GORYEO. In order to cope with the harassment, GORYEO organized Pyolmuban (a special militia), that is, GORYEO made preparations for a large-scale expedition against Yojin. This campaign was carried out by Yun Kwan (2nd year of YEJONG, 1107). Yun Kwan was able to construct 9 forts and stationed troops in them during his campaign. However, these forts were later returned to Yojin control (4th year of YEJONG, 1109).

     After this incident, Yojin was unified by Agolta who founded Kum (1115). Kum overthrew the Kitan and began exerting pressure on GORYEO. It forcibly demanded military alliance with GORYEO. Judging that external peace was advantageous to the existing political regime, the court, led by LEEJAGYEOM, accepted Kum's demands (4th year of , 1126). With this move, there were no more military invasions by Kum.

     From the beginning, GORYEO had always tried to maintain friendly relations with the Sung Dynasty. GORYEO wanted to satisfy its own cultural development and since it considered the Sung Dynasty to be a culturally advanced nation, friendly relations were maintained. Visits by travellers were suspended at times due to the internal situation in Sung, but overall friendly relations and trade were maintained. Arabian merchantmen trading with Sung, sailed as far as to the Yesong port, the sea door to Kaegyong.

8) LEEJAGYEOM and Myo Chong Rebellions

     In the golden age of the aristocratic culture (during the eras of INJONG (1122-1146) and UIJONG (1146-1169)), rebellions caused by conflicts and internal troubles amongst aristocrats broke out one after another. The first rebellion was led by LEEJAGYEOM, the head of the Inju Lee clan. He made his daughter King YEJONG's queen and had INJONG, her son, placed on the throne. He again gave two daughters to INJONG, thus consolidating his power with the double relations. His arrogance made him believe in a prophecy that he would one day be king and he began to entertain the ambition to take the throne. INJONG, with the help of his aides, tried to eliminate him, but failed. However, LEEJAGYEOM was later ousted by Chok Jun Gyong, one of his followers (5th year of INJONG, 1127).

     After the death of LEEJAGYEOM, Myo Chong and others proposed that the capital be moved from Kaegyon, where the royal palaces had been burned down, to Sogyong. Based on geomancy, he claimed that the auspicious effect of Kaegyong had been weakened but that of Sogyong was thriving. Hence, by moving the capital to Sogyong, it would be possible to revive the nation. He also insisted on calling the king emperor, naming a new era in order to be on equal footing with Sung. He also insisted on conquering Kum. Myo Chong and his followers were designated as the group of Sogyong, geomancy and anti-foreigner spirit.

9) Revolt of the Military Leaders and Military Regime

     Civil administration based aristocracy caused the decline of the military leaders influence, and as time went by, their grievances and discontent grew. As early as the 5th year of HYEONJONG (1014), there was a coup d'etat led by CHOEJIL and KIMHUN.

     In the 24th year of UIJONG (1170), a revolt by military leaders broke out. When the king went to Pohyonwon, generals accompanying him such as Chong Jong Bu, LEEUIBANG and Lee Ko rose in revolt demanding their followers to "kill everyone with a civilian hat" They deposed UIJONG and enthroned MYEONGJONG. The 3 leaders of the revolt (Chong Jong Bu, LEEUIBANG, Lee Ko) then led the political regime which was centered in Chungbang, However, disagreements occurred amongst them and Chong Jong Bu was killed by Kyong Dae Sung after Kyong Dae Sung gained power for himself.

     Kyong Dae Sung tried to ensure his personal power and safety by establishing Tobang, but he died of illness. On his death, Lee Ui Min moved to the capital and took power. Lee Ui Min was a man of humble birth. During his reign, he ruled tyrannical. Lee Ui Min was eventually killed by 2 brothers, Choi Chung Hyon and Choi Chung Soo (26th year of MYEONGJONG, 1196). With the appearance of Choi Chung Hyon, the confusion amongst the military leaders subsided for the time being.

     Choi Chung Hyon deposed the 2 kings MYEONGJONG and UIJONG and enthroned 4 kings, INJONG, Hoijong, GANGJONG and GOJONG. The throne became no more than a puppet seat without any real power. The royal facade, however, was maintained because of the tradition of a long royal lineage. Choi Chung Hyon suppressed the power of the Buddhist temples and subjugated farmers and servants uprisings. Using his power, he granted government positions and promoted Hyang, So and Pugok to Hyun.

     The Choi clan regime lasted 60 years, spanning four eras. Civilian officials and domestic servants that the regime won over to its side became closely akin to feudal retainers rendering devoted service. The Choi clan regime controlled Tobang, Chongbang and Sobang, which were centered around Hongnyongbu. They reigned over both civil and military aristocrats.

     The phenomenon of farmers leaving land and becoming vagabonds was already evident during the YEJONG era (1105-1122). Robber gangs formed by groups of vagabonds caused disruptions at various places. Stimulated by the revolt of the military leaders, they similarly rose in large-scale revolts in several places. In the 2nd year of MYEONGJONG (1172), uprisings by the people broke out in Changju (Shangsong), Songju (Songchon) and Cholju (Cholsan). These were the first uprisings that broke out under the military regime. The cause was indignation over the oppression by local officials. In the 6th year of MYEONGJONG (1167), the Mangyi and Mangsoyi rebellion broke out at Myonghakso of Kongju and spread throughout the country. In the 12th year of MYEONGJONG (1182), a rebellion, led by soldiers and man servants of government employees, broke out in Chonju.

     In the 23rd year of MYEONGJONG (1193), the KIMSAMI and Hyo Shim rebellion, which showed a new aspect, broke out. That is, in this rebellion, the rebel armies attempted to unite and form a common battle line, thus making the revolts more consistent. Initially, KIMSAMI rose in revolt at Woonmun (Chongdo) while Hyo Shim rebelled at Chojon (Ulsan), but they later joined forces enhancing their numbers to about hundreds of thousands of soldiers. After this, farmers uprisings continued at several places all over the country.

     A rebellion broke out in Kaegyong also. This was the Manjok revolt which occurred in the first year of ShINJONG (1198). This rebellion is significant in that all the male and female slaves in Kaegyon contacted one another and rose together to liberate their social status and seize political power. They, however, were detected in advance and failed to carry out their plans but they left a famous speech: Are there different breeds of generals and ministers? When the time comes anyone can become a general or minister. This rebellion was completely subjugated but it indicated that the foundation of GORYEO was shaking.

11) Contention with Mongolia

     Mongolia, that grew up in the grasslands of North Asia, once maintained friendly relations with Koyro. However, in the 18th year of GOJONG (1213), it demanded excessive tributes, and invaded GORYEO on the pretext of the death of one of its envoy on his way home. During the next 30 years, Mongolia invaded GORYEO 6 times. The ravages of war, including the destruction of cultural properties, were beyond description.

     In the 19th year of GOJONG (1232), GORYEO transferred its capital to GANGHWADO so as to continue its fight against Mongolia. GORYEO decided to take advantage of Mongolia's fear of the sea. Nobles took refuge in GANGHWADO and the people were instructed to retire to mountain fortresses or islands. With the support of farmers, the Choi clan fought against Mongolia. The cry to overcome the national crisis with the help of Buddha led to the publication of a collection of all the sacred writings of Buddhism. Hence, the Tripitaka Koreana, kept at Haeinsa temple, was published.

     When Choi Ui, the last ruler of the Choi clan, was killed by YUGYEONG and KIMJUN, the military regime of the Choi clan came to an end (45th year of GOJONG, 258). Political power was once again returned to the king. With this development, the court decided to make peace with Mongolia. In the following year, the crown prince, prince Chon, was sent to Mongolia to convey GORYEO's intention for peace. Also, the fortress at GANGHWADO was razed to the ground as a symbol of non-resistance. In the 11th year of WONJONG (1270), the military regime collapsed completely and GORYEO returned to Kaeqyong. Hence, resistance against Mongolia was completely abandoned.

12) Interference by Yuan and Influential Families

     GORYEO was officially not under the direct control of Yuan. However, Yuan had many means of controlling GORYEO. They send princesses of Yuan to be queens and arranged formalities appropriate for a son-in-law nation. They directed GORYEO to use the feudal structure instead of an imperial structure system. They insisted that Mongol be used at the royal household and changed the clothing and hair styles to that of Mongolia's.

     When Yuan invaded Japan, it established a government agency called Chongdong-haengsong, and it controlled the internal affairs of GORYEO through this office. In addition, Yuan occupied part of GORYEO territory and directly governed that territory. The agencies that governed that territory included Ssangsong-chongkwanbu, Tongnyong-bu and Tamra-chongkwanbu.

     This territory was recovered eventually through persistent efforts by GORYEO. During the time Yuan interfered with the governance of GORYEO, a new ruling class, comprising of the influential families of GORYEO, emerged. They secured high positions and power, possessed vast lands and wielded their power over the whole nation. Making the best of the Umso system, they managed to monopolized wealth and power from one generation to the next, and solidified their power through marriages with the royal family or amongst themselves.

     Their wealth was based entirely on land. They forcibly mobilized the people to reclaim wasteland or wrenched land from others. The lands they acquired this way were called `farms' and were bounded by mountains and rivers extending over several counties. As a result, the living conditions of the ordinary people worsened .

     It was only natural that discontent and criticisms against Yuan and the influential families intensified. Anti-Yuan reform movement led by GONGMINWANG came to fore and a new class with new ideals took shape in the background.