고구려 후기 대외관계는 지배층의 정치적 이해관계와 국제관계가 맞물려 상호 연동하며 전개되고 있었다. 고구려를 둘러싼 국제질서는 크게 서북방유목세력과 중원왕조의 길항관계 속에서 규정되었다. 중원이 남북조로 분열되어 있는 동안 북방은 유연→돌궐로의 세력교체가 이루어지고 있었으며 서방에서는 토욕혼이 중요한 위상을 차지하고 있었다. 이러한 안정된 국제질서의 틀 속에서 고구려 내부에서는 지배층간 갈등과 모순이 권력다툼으로 표출되었다. 6세기 전반 전제왕권이 무너지고 왕이 시해되면서 귀족연립정권이 성립한 데는 이러한 외부적 요인도 눈여겨보아야 한다.

안정적이던 국제질서는 수가 중원을 통일하면서 변동이 일어났다. 이러한 정세 변동에 발맞추어 고구려 내부에서도 외부에서 밀려오는 힘에 대한 경계심이 늘어나고 그에 따라 권력의 일원화 현상이 일어나게 되었다. 평원왕 이후 영양왕대에 이르는 고구려 왕권의 안정은 이와 무관할 수 없다. 영류왕대 후반 당의 위협이 고조되는 가운데 연개소문이 정변을 일으켜 독재정권을 수립했던 상황도 권력 일원화로 파악할 수 있다. 이 글에서는 이러한 관점아래 고구려의 ‘內政’과 ‘外政’을 상호 연동시켜 바라봄으로써 각 시기별 고구려 안팎의 모순관계가 어떻게 수렴되어 갔는지를 검토하였다.

1장에서는 5세기 말에서 6세기 전반 전제왕권이 동요하는 배경과 대남북조외교의 전개과정을 살펴보았다. 문자왕대를 지나면서 왕권의 약화조짐이 보이고 531 년에는 안장왕이 피살되기에 이르렀다. 이렇듯, 전제왕권이 동요하게 된 데는 장수왕대 왕위계승의 안정성을 확보하기 위해 단행된 대대적인 귀족숙청과 문자왕대 악화되기 시작한 남북방관계가 고구려 내부의 불안감을 가중시켰기 때문이다. 이를 타개하고자 안장왕은 적극적인 대내외정책을 통해 왕권을 뒷받침할 지지세력을 확보하고자 정계개편을 시도하였지만 실패하였다. 아울러 대남북조외교의 변화 역시 이러한 고구려의 내부상황과 밀접하게 맞물려 있었다.

2장에서는 귀족연립정권의 성립과 대외관계를 살펴보았다. 안장왕이 피살되자, 안원왕은 귀족들의 추대를 받아 즉위하였으며 이로써 귀족연립정권이 성립하였다. 안원왕대 잦은 天災로 인한 정국불안은 왕위계승분쟁으로 비화되었으며 추군측의 지원을 받아 양원왕이 즉위하였다. 한편, 6세기 전반 육진의 난으로 북위는 동ㆍ 서위로 분열되었으며 북방에서는 유연이 몰락하고 돌궐이 등장하는 등 대륙정세가 크게 요동쳤다. 이와 연동하여 한반도 내 백제ㆍ신라 연합군은 고구려가 장악한 한수 유역을 점령하였다. 이러한 상황 속에서 양원왕은 왕위계승분쟁 및 외척 세력의 발호로 인한 왕권의 약화를 극복하기 위해 밖의 위기를 활용하고자 하였다.

3장에서는 평원왕대 이후 왕권의 강화와 수의 중원통일에 따른 대외관계의 변동과정을 살펴보았다. 평원왕대 고구려 국정은 안정을 되찾았으나 돌궐이 등장하여 북방을 장악하면서 국제관계는 재편의 계기를 마련하였다. 이와 함께 신라가 남북조에 견사하며 새롭게 국제무대에 등장하였으며 백제는 북조와 교류하기 시작하였다. 6세기 후반 돌궐이 분열되고 수가 중원을 통일하면서 국제관계는 또다시 재편되었다. 그런 가운데 고구려는 대수강경정책을 취하며 고구려적 질서를 지켜나가기 위해 수나라와 4차례에 걸친 전쟁을 치르게 되었다.

4장에서는 연개소문 정변을 통한 고구려 내부권력의 일원화현상과 멸망과정을 살펴보았다. 영류왕대 고구려는 對隋戰爭에 따른 과제를 안은 채 출발하였으며 對唐戰爭으로 이어지는 과도기에 처해 있었다. 고구려의 대당관계는 630년 당 태종이 동돌궐을 복속시킨 것을 계기로 적대관계로 돌아섰다. 이후 대외적 긴장감이 높아져 가는 가운데 ‘대대로’ 선출 및 왕실의 후계구도 문제가 불거지면서 연개소문이 돌연 쿠데타를 일으켜 영류왕을 시해하고 정권을 장악하기에 이른다. 보장왕 즉위 이후 연개소문정권은 대당강경책을 유지하였다. 그러나 연개소문의 죽음과 함께 고구려는 내분에 휩싸였다. 그 결과, 고구려는 신라ㆍ당연합군의 침략을 막지 못한 채 멸망하였다.

The foreign relations of the latter part of Koguryo had developed according to the political interests of the ruling class and international relations. I wish to study what solved the inside and outside conflicts of Koguryo.

The time period covered is from the late 5th century when royal power began to weaken to A.D 668 when Silla(新羅) joined hands with the Tang (唐) dynasty to destroy Koguryo. The scope of study includes all nations having relations with Koguryo. From a dynamic standpoint, I will analyze international relations on the basis of documentary records.

The foreign relations of the latter part of Koguryo will be divided into four periods, the period of weakened royal power, the aristocratic coalition period, the period of strengthened royal power, the dictatorship period, in consideration of the internal and external situation.

Chapter one examines the internal situation of Koguryo where royal authority began to weaken and Koguryo's relations with the Southern and Northern Dynasties(南北朝) from the late 5th century to the early 6th century. The royal power of Koguryo during the reign of King Munja(文咨 王) was weak when compared with that of King Jangsu(長壽王). In my opinion, King Jangsu purged the aristocratic nobles for safe succession to the throne by his grandson. This incident caused internal unrest. Besides, King Munja who succeeded to the throne after his grandfather sometimes came into conflict with the Northern Wei(北魏) of Hsiaowen ti(孝文帝)’s reign.

But both countries resumed friendly relations during the latter term of King Munja's reign. This was because Mulgil(勿吉) threatened Koguryo so as to secure the trade route to the Northern Wei. And then Silla made an alliance with Baekjae(百濟) and pressed Koguryo from the south. Much like Koguryo, the Northern Wei of Xuanwu ti(宣武帝)’s reign also fell into confusion due to internal rebellions.

King Anjang(安臧王) who succeeded to the throne after his father began to strengthen royal authority. Koguryo established diplomatic relations with the Southern and Northern Dynasties and watched the development of the situation in the 520's. As the Northern Wei fell into disorder and civil war, Koguryo broke off diplomatic relations with Northern Wei. Accordingly, Koguryo dispatched an envoy to Yang(梁) in 526, groping for a change in foreign policy. Meanwhile Koguryo made full defensive preparations and on the other hand it attacked Northen Wei. In this manner, Koguryo kept close watch over the movements of Northen Wei.

King Anjang attacked Baekjae which had undergone a change of the throne. As a result, Koguryo occupied the Han river(漢水) valley. In addition, King Anjang made a tour of the country so as to see how the people were living, after he had worshipped at the ancestral shrine of the royal family. But, he was assassinated in 531 and political reform was stopped. It seems King Anjang was assassinated by those who opposed his foreign policy.

Chapter two discusses the aristocratic regime and foreign relations of Koguryo in the middle 6th century. King Anown(安原王) succeeded to the throne with the help of royal in-laws. However, Koguryo met with frequent natural disasters during his reign. From this we know that royal power was weakened.

As a result, Koguryo dispatched an envoy to Northen Wei in 532, groping for a change in foreign policy. Since then Koguryo dispatched envoys to Eastern Wei(東魏) every year. Because Baekjae and Silla were busy fighting each other over Gaya(加耶), relations with Koguryo were stable. Since Baekjae attacked Koguryo in 540, the relations between the two countries grew worse.

Around the 540s Koguryo fell into inner conflict resulting from the matter of succession to the throne and the election of Daedaero(大對盧). In addition, there was a sudden change in the international situation. For example, Rouran(柔然) collapsed and the Turks(突厥) newly emerged, and there was a change of dynasty in China from the Yang(梁) to the Jin(陳). Silla made an alliance with Baekjae after which they attacked Koguryo in 551 and occupied the Han river(漢水) area. At the same time Koguryo and Peich'i(北齊) were in sharp conflict of opinion over the repatriation of drifting people. King Yangwon(陽原王) was faced with providing a solution to this domestic and international crisis.

King Yangwon began to strengthen royal authority during his reign. In the evaluation of historians, he is cast in a heroic mold and has a great figure, which suggests that he had proven himself in his power struggle with the nobility and may well signal some change in the political landscape. As a matter of fact, King Peongwon(平原王) who succeeded to the throne after his father, created a stable political situation, because King Yangwon had removed the influence of his in-laws and paved the way for significant progress in royal authority. It seems that the international situation had an effect on the domestic political landscape. Namely, Koguryo coped with the rapid changes of the international situation with the king as the center.

Chapter three investigates the strengthened royal power after King Peongwon and the international situation fluctuated by means of unified Sui(隋) China. I focused on the trend of Liao-hai(遼海) which affected not only each nations interests but was also susceptive to changes of the international situation. In addition, I examined the movements of Silla and Baekjae in relation to this trend.

Koguryo was in a transitional period during which the period of the Southern and Northern Dynasties ended and unified Sui China emerged during the reign of King Peongwon. Koguryo needed to change the focus of its foreign policy to serve the international situation. Namely, during the Southern and Northern Dynasties of China where North and South were pitted against each other, Koguryo focused on relations with Silla and Baekjae. But as China began to be unified, Koguryo began to pay more attention to improving relations with the Turks and coping with the Sui Dynasty.

The royal authority of Koguryo had laid a solid foundation during King Peongwon's reign. King Peongwon who succeeded to the throne after King Yangwon, created a stable political situation, because King Yangwon had removed the influence of his in-laws and paved the way for significant progress in royal authority. As a result, Koguryo was able to cope with the rapid changes of the international situation with strengthened royal authority during King Peongwon's reign.

Between Koguryo and Sui major wars broke out four times during King Yeongyang(嬰陽王)’s reign. Many scholars have concentrated on research on the relations between the two countries because this led directly to the fall of the Sui dynasty. Until now most research covers the military background of the Sui expedition to Koguryo. The reign of King Yeongyang of Koguryo will be divided into two periods in consideration of the Sui reigning emperors.

I examined the tale about Kim yusin(金庾信)'s birth in the Samgukyusa(三 國遺事). This tale is an indication of the differences of opinion in Koguryo concerning relations with the Sui dynasty. Koguryo during the reign term of King Yeongyang took a hard-line policy toward the Sui. Thereupon Koguryo delivered an attack against Liaoxi(遼西). At once Sui Wenti(文帝) led a large force and invaded Koguryo territory. The Sui expedition force failed not only because of the monsoon season and supply problems but also because of the Turks.

I discussed the political situation during the latter reign term of King Yeongyang and the war with the Sui. King Yeongyang took a hard-line policy toward the Sui all through his reign. On such a framework Koguryo devoted all its might to omni-directional diplomacy. Koguryo made use of animosity between Baekjae and Silla. Namely, Koguryo entered into friendly relations with Baekjae and Wae(倭), thereby restraining Silla. Koguryo began to pay more attention to improving relations with the Turks and coping with the Sui Dynasty.

As a result, Sui Yangti(陽帝) attacked Koguryo three times, all ending in complete failure. Thereby Sui was on the road to collapse. Also as a result of prolonged warfare, Koguryo's national power declined and its economic foundation was weakened. As a result, Koguryo was likely to thrust into the vortex of political instability during the end reign of King Yeongyang.

Chapter four studies the fall of Koguryo. Koguryo during the reign of King Yeongryu(榮留王) was placed in a transitional period which led to Tang Tai-tsung(太宗)'s interventions in Koguryo. The international situation fluctuated in accordance with relations between Tang and the northwest countries and tension built up in the Korean Peninsula as well. Therefore Koguryo had to exert all it's energy to strengthening it's regime domestically and externally to establishing new relations with the Tang.

In the meantime, scholars have studied Koguryo-Tang relations from many different aspects. Generally it is understood that, after Tang conquered the Eastern Turks(東突厥) in A.D. 630, relations between the two countries turned hostile. Koreans scholars have viewed Koguryo's political situation in relation to it's foreign policy where a moderate faction and hard-line faction existed, and attempted to analyse this through the confrontation between King Yeongryu and Yeongaesomun(淵蓋蘇文).

But, it is not yet thoroughly understood what effect the presence of the northwest countries had on Koguryo-Tang relations. The reign of King Yeongryu of Koguryo will be divided into two periods in consideration of the reigning Tang emperors. Koguryo-Tang relations of each period will be thoroughly examined.

I examined the leading political forces of Koguryo. As a result, it became clear that contrary to established notions, relations between the Yeon family(淵氏家) and King Yeongryu were cooperative. It is also understood that the Daedaero acted as a spokesman for the king.

I discussed Koguryo-Tang relations during the first term of King Yeongryu's reign. Both countries maintained friendly relations because the political confusion at the end of the Sui and the early years of the Tang; the Eastern Turks were also expanding into Liao-hai.

I investigated Koguryo-Tang relations during the latter term of King Yeongryu. Tai-tsung took up an agressive attitude toward foreign policy after seizing power through a coup. After Tang conquered the Eastern Turks in A.D. 630, Koguryo broke off diplomatic relations with the Tang and watched the development of the situation. As the Hsüeb-yen-t'o(薛延 陀) arose in place of the Eastern Turks and expanded into Tang's northern border, the two countries felt uneasy and therefore Koguryo and Tang resumed diplomatic relations and the dispatching of envoys.

Yeongaesomun assassinated King Yeongryu in A.D. 642 and seized power through a coup. King Bojang(寶藏王) succeeded to the throne with the help of Yeongaesomun. With this, he established a one-man dictatorship regime. Tang Tai-tsung invaded Koguryo on the pretext of the king's assassination in A.D. 645. Koguryo also took a hard-line policy toward the Tang.

After Tang Gaozong(高宗) succeeded to the throne, relations with Koguryo entered a new phase. But Silla joined hands with Tang to destroy Baekjae in A.D. 660. and Koguryo fell into internal conflict after Yeongaesomun's death in A.D. 665. As a result, Koguryo was destroyed by the allied Silla-Tang forces in A.D. 668.