From the early stage of the SAMGUK period, unremitting rivalry and wars had characterized the relationship among SAMGUK. One kingdom was allied with another against the third, but the alliance had never been put on a solid bedrock. There had been dynamic changes constantly altering the relationship among SAMGUK. GOGURYEO ajacent to Asian land mass was beleaguered by continental powers. While GOGURYEO was engrossed in fighting against the northern continental powers, BAEKJE attacked SINRA. SAMGUKUIJAWANG of Paekche, called "the Wise of the East" launched surprise attacks on SINRA and occupied 40 prefectures including Dayasung, the fortress of strategical importance. The mighty BAEKJE drove SINRA into stalemates.

      King Muyol of SINRA launched a diplomatic mission by going in person to GOGURYEO in an attempt to solicit GOGURYEO to render its helping hands in his campaign against BAEKJE. Yonkesomun, a general who held reigns of GOGURYEO, demanded tha part of the territory which had been taken by SINRA be returned in return for his participation in the campaign. But King Muyol's diplomatic effort was abortive. He went to China and asked for its help in his campagin against GOGURYEO. Having been defeated by GOGURYEO many times, T'ang Dynasty had no reason to rebuff his request. The two kingdoms entered into ties of alliance. While guranteeing its promise for support, T'ang was flexing its muscle to change SINRA's campaign strategy in a way that stressed attack on the back of the enemy rather than frontal attack. The ultimate goal of T'ang behind its help was to occupy SINRA and pacify the Korean peninsula under its reign.

2) Downfall of BAEKJE and Movement for Restoration

      SAMGUK UIJAWANG, as aforementioned, actively engaged in warfares against SINRA with the resultant enlargement of his territory. But frequent warfares impoverished the life of his own people and incurred their wrath. He exulted in his own achievement and his self-indulgent and extravagant life knew no bounds. There was a saying "his days are numbered." Further, natural disasters drifted its situation worse and faciliated the downfall of the kingdom.

      SINRA on the other hand was well aware that it was coming for a high time to attack BAEKJE. GOJONG of T'ang Dynasty, ordered Sojongbang, the commanding general of T'ang forces to hit BAEKJE in 660. SAMGUKUIJAWANG had been in his reign for 20 years by that time. T'ang launched a massive attack commanding l30,000 strength of army and navy. When T'ang forces were balking at Dokjok Island, KIM YUSIN, the SINRA general, was approaching the capital of BAEKJE with his forces of 50,000.

      SAMGUKUIJAWANG defied the tearful appealing of the two most loyal subjects, SEONGCHUNG and Hong Soo, for making a timely preparation to save the kingdom. When he was awaken from his long slumber, he found it too late to take any action. He had no alternative but to have Kaebak lead a suicidal contingent of 5000 strength. But the suicidal contingent was a helpless pawn before the outnumbering forces of SINRA and T'ang. All of the suicidal contingent fought heroically to its last soul.>

      The combined forces of SINRA and T'ang swarmed into Buyo, the capital town of Paekche. SAMGUKUIJAWANG and his royal subjects barely escaped the capital town and defected to Woongjin. Not long before, he urrendered. Sojongbang, the T'ang's general, took away SAMGUKUIJAWANG, princes, subjects and civilians to T'ang as hostages. T'ang had its troops stationed at Woongjin and ruled over that part of the kingdom for a good while.

      To counter the occupation of BAEKJE by SINRA and T'ang, BOKSIN, a member of the royal family, and DOCHIM, a Buddhist monk, rallied insurgent soliders into a resistence movement. They summoned Prince P'ung who had been in Japan and enthroned him to the king. The resistence movement gathered force rapidly and restored 200 prefectures. However, it was not long before it began tapering off and eventually amounted to nothing due to internal conflicts between the leaders of the movement: BOKSIN killed DOCHIM and P'ung killed BOKSIN. Losing no time in taking this opportunity, the allied forces of SINRA and T'ang attacked the citadel of resistence, Buhungkun, putting an end to the four-year resistence movement.

      GOGURYEO consumed the ardor of its people to fight due to its frequent engagement in armed confrontationss with its neighbor powers. It was not only Sui and T'ang Dynasty that confronted GOGURYEO: Other continental powers posed serious threats to the very survival of the kingdom. Paesants were hardly given a breathing spell to engage in farming, and their life were miserable. GOGURYEO became the target of invasion by T'ang across the sea and by SINRA in the south.

      The sudden death of YEONGAESOMUN left his sons and aristocratic members entangled in chaotic and desperate struggles for hegemony. Namsang, his first son, succeeded his father but ran away to China after plagued by internal strifes with his brothers. Yonjongto, his younger brother, who had ruled over l2 prefectures, surrendered to SINRA. GOGURYEO became a teethless tiger.

      T'ang's armies, boasting 500,000 strength, crossed APROKGANG and swarmed into PYEONGYANG. The allied forces of SINRA and T'ang were fighting their way from the south. PYEONGYANG was encircled by the hostile forces. The armies and paesants of GOGURYEO fought out heroitically to the end. But BOJANGWANG, and his retainers surrendered. T'ang established its commandery on the site of GOGURYEO and ruled over it for quite a while.

4. War Between SINRA and T'ang

      After the two kingdoms collapsed, T'ang began to belie its disguised scheme to deprive SINRA of its territory. T'ang demanded that SINRA return Biyolsung, which it argued had been a domain of China to Andong, where T'ang's army was stationed. At Woonjin, the old capital of BAEKJE, T'ang's soldiers removed a stake marking the borderline between the boundary of SINRA and that of T'ang. T'ang went to greater lengths to appease the lord of HANSEONG into allowing T'ang's army to occupy the domain.

      T'ang's unabashed claim to its territory angered SINRA. It was about this time that forces of GOGURYEO descent were engaged in armed confrontations with T'ang's army. Battles were escalated into the extent that forced T'ang to move its commandery from Andong to Liaotung. From this time on, the allied forces of SINRA and GOGURYEO descent were embattled against T'ang army.

      ANSEUNG, son of BOJANGWANG, came to SINRA with 4,000 peoples. Army under the command of KOYEONMU advanced across APROKGANG to Manchuria together with the SINRA's army. GEOMMOJAM rallied with insurgent paesants, killed T'ang's officials and defected to SINRA. GEOMMOJAM enthroned ANSEUNG to the king and declared his campaign to restore GOGURYEO. At the same time, he dispatched an offical to SINRA on a mission to negotiate with an intention to make his domain part of SINRA's territory. KOYEONMU who led revolting peoples became a general loyal to ANSEUNG.

      To block T'ang's scheme, SINRA provided outright support for the restoration of GOGURYEO. A new form of alliance was forged between SINRA and GOGURYEO. SINRA had already accepted ANSEUNG as the king of GOGURYEO. A massive armed confrontation took place when advance by the allied forces of T'ang and MALGAL people estimated at 40,000 were arrested by those of SINRA and GOGURYEO in 672. This battle ended up with the latter's victory. In scattered skirmishes, T'ang's armies were driven back aross the northern border.

      In 672, GOJONG of T'ang declared KIMINMUN, a younger brother of King Munmoo of SINRA as the new king of the kingdom. It was an outright intervention into the internal affairs of SINRA, the kingdom with its own sovereignty. This declaration belied its intention to treat SINRA as its protectorate. Following the declaration, T'ang sent its armies invading SINRA. SINRA had been bracing itself for this clash and was able to fend off T'ang's invaders. SINRA had driven away all T'ang forces from its territory south of the Taedong River.

      SINRA brought the territory south of the Taedong River under its reign. But the vast territory in the north slipped its grip. The land between Liaotung and the Taedong River was left under the control of T'ang. To manage the land, T'ang established Andong commandery but the incessant parry and thrust of GOGURYEO descendents forced it to move to Liaotung.
      T'ang migrated 28,000 households of the GOGURYEO descent into its territory west of Liaotung, which had been inhabited by GEORAN and MALGAL peoples. The inhabitants in this region suffered the relentless exploitation of the feudal lord. In May 695, GOGURYEO descendents joined hands with GEORAN and MALGALs in a popular revolt against the feudal lord. Lee Jin Chung, Chieftain of GEORAN tribes occupied the lord's castle and proclaimed himself as the king of GEORAN Kingdom. The GOGURYEO descendents and MALGAL people moved toward northeast and occupied several domains under the reign of T'ang.

      In order to suppress revolts, T'ang dispatched massive forces. T'ang's army defeated MALGAL people and traced the persistent elements of GOGURYEO descent. But its advancing troops encountered a heroic performance in battle by DAEJOYEONG, a general of GOGURYEO descent. Having repelled T'ang's army, DAEJOYEONG founded a new kingdom called "Chin" in 698 on a mountain foot near Donwha Prefecture of Kilim Province. In 7l3, it changed its name into "BALHAE."

      GOGURYEO descendents and MALGAL people constituted the majority of people in BALHAE. Although GOGURYEO descendents were outnumbered by MALGAL people, they were in the ruling class by monopolozing higher echelons of the political system. GOGURYEO descendents renewed their determination to restore the glory of the old GOGURYEO. The official message it sent to Japan reflected the aspiration for the restoration of the old territory.

      BALHAE was embattled against T'ang. MUWANG (7l9-737) of T'ang dispatched navy fleet to concquor BALHAE. BALHAE was also pitted against SINRA. Tension and rivalry chracterized the relationship between the two kingdoms. The tension-ridden relation provoked SINRA into building stone walls along its borderline. BALHAE found itself in the beleaguored state of the old GOGURYEO between T'ang and SINRA and attempted to forestall possible invasions by forging alliances with Dolkwol and Japan. It was much later that BALHAE traded with SINRA.

      Under the reign of King Mu, BALHAE became a mighty power whose territory reached the northern part of Manchuria. BALHAE introduced T'ang's culture and ruling systems to lay a solid institutional base to further the development of the kingdom. Under the reign of King Son (8l8-830), BALHAE reached the height of its prosperity with its territory bordering on the present maritime Siberia in the east, the Hukryong River in the north, and Ham Kyung Nam Do in the south.