In 37 B.C., Jumong (朱蒙, 주몽), the greatest hero in Korean history, led a branch of ancient Korean people to extricate themselves from the control of the Han Empire, and founded a country named “Koguryo” (written as "高句骊" or "高句丽" in Chinese) in the Northeast Asia. The new country continually expanded its territory, and later occupied the northern part of modern-day North Korea and a part of modern-day Jilin and Liaoning Provinces of China.
In A.D. 8, the last young emperor of the Western Han Dynasty had to abandon his throne. Wang Mang (王莽), a great idealist and an unswerving reformer, ascended to the throne through a peaceful way, and named his empire “Xin” (新) which means “new”. This emperor had a thirst for revived the systems and proprieties of the Zhou Dynasty. So he reformed his country on a large scale, and even the inherent societal system of landed private ownership was shaken by him. This is why so many persons have hated and reviled him for two thousands years. In the last days of the Western Han Dynasty, because of the decline of the country, many foreign countries were disrespectful to China. The Huns often annoyed the border of the Han Empire, and the countries of the Middle Asia started to try to extricate themselves from the control of the Han Empire. When Wang Mang became the emperor of China, he decided to rebuild the prestige of the great empire. According to the Zhou Dynasty’s principle “There are not two suns in the sky, so there are not two kings in the Zhou Kingdom”, Wang Mang demanded the kings of the countries which had submitted themselves to the Han Empire in the past to change their title to “Hou” (侯, a title of a feudal monarch). The policy exasperated other countries. These countries severed diplomatic relations with the Xin Empire.
In order to subjugate these countries, Wang Mang mobilized many troops, and forced Koguryo which still kept friendly relationship with China to send an army to attack the Huns. The armymen of Koguryo were not willing to fight for China, so they ran away and returned to their country. Many of them even annoyed the border of China. A local prefect led his army to chase the army of Koguryo, but he was unfortunately killed by the armymen of Koguryo. Wang Mang was very angry. His minister Yan You (严尤) advised Wang Mang to appease Koguryo, but Wang Mang refused. He ordered Yan You to lead army to punish Koguryo. Yan You knew there were battles in the extensive borders of the north, the northwest and the southwest, and the empire needed the peace of the northeast. So he didn’t want to let his armymen fight, and he trapped and killed the king of Koguryo. Wang Mang was pleased, and renamed Koguryo “Xiaguryo” (下句骊). In Chinese language, “Ko” (高) means “high”, and the character “Xia” (下) in this name means “lower”. The death of the king and the insolent action of China infuriated seriously the people of Koguryo, so since then, the army of Koguryo often harassed the border untill the Eastern Han Dynasty was built in A.D. 25.
In 108 B.C., China annexed Joseon and divided it into four regions. Later the regions were merged into a region named “Lelang Jun” (乐浪郡, “Jun”[郡] was the name of an intermediate region). After the decline of the Han Empire, Koguryo gradually nibbled at the land of Lelang Jun. in A.D. 316, the Western Jin (西晋) Empire collapsed, and the north of China was captured by several foreign nations. The later Eastern Jin (东晋) Empire was not able to control the land in the Korea Peninsula. Koguryo took the chance and seized the whole of Lelang Jun. Since then, the north of the Korea Peninsula was completely occupied by Koguryo, and this country became a very strong country in the Northeast Asia.
In the early days of the Sui Dynasty which was built in 581, Koguryo submitted itself to the powerful empire, and Sui Wen-Emperor (隋文帝) renamed Koguryo “Koryu” (高丽). After the death of the old king of Koryu, the new king Yuan (元) was an arrogant man. He actually led his army to invade the border of China. Sui Wen-Emperor was very angry, and sent army to attack Koryu. However, the supplies were not enough, and the army met an epidemic disease, so the armymen were depressed. This military action caused Yuan to be anxious. He apologized to China. Sui Wen-Emperor withdrew his army and treated Koryu as before.
When Sui Yang-Emperor (隋煬帝) who was a tyrannical man ascended the throne, Yuan actually was irreverent to this emperor. So this cruel emperor decided to make retaliate. In 611, the war was started. Yang-Emperor went to Liaodong (辽东, the east of modern-days Liaoning Province) and commanded his army by himself. The army of Sui Empire was divided into several parts and invaded Koryu by several routes. The armies of Koryu were defeated successively, and they had to withdraw into their cities and defended them tenaciously. Yang-Emperor ordered his army to attack these cities, but he told his generals, “If the armymen of Koryu surrender, you must conciliate them at once, and don’t use force again.” When a city would be captured by the army of the Sui Empire, the armymen of Koryu said they wanted to surrender. Because of the order of Sui Yang-Emperor, the general had to report the information to the emperor. When the emperor decided to conciliate the armymen of Koryu, the army of Koryu had strengthened preparedness against the army of Sui, and refused to surrender. Sui Yang-Emperor actually didn’t find the purpose of the enemy. After a long time, the army of Sui Empire started to lack supplies, and the armymen were war-weary. The army of Koryu took the chance to attack the Sui’s army and defeated them continuously, so Sui Yang-Emperor had to withdraw his army.
In 613, Sui Yang-Emperor led army to attack Koryu by himself again. This time Sui Yang-Emperor ordered his generals to act as they see fit. The army still invaded Koryu by several routes. The generals of Sui didn’t believe the lies of the armymen of Koryu, and attacked the cities fiercely. The army of the Sui Empire advanced successfully, and it seemed that the whole Koryu would be captured. However, Yang-Emperor heard a bad news that Yang Xuangan (杨玄感), the minister who superintended military supplies of this war, rebelled in Liyang (黎阳, this city belonged to modern-days Henan Province) and attacked Luoyang (洛阳) which was the new capital of the empire. The emperor was very scared, and ordered his army to return and suppress the rebellion. Hu Sizheng (斛斯政), a minister who superintended military affairs, was the friend of Yang Xuangan, and he was against the tyranny of Yang-Emperor as Yang Xuangan. When Hu Sizheng heard the news, he was worried that he would be involved. So he ran away to Koryu, and told much military information to the king of Koryu. Koryu dispatched picked troops to chase and attack the army of Sui, and inflicted heavy losses on the rearguards of the Sui’s army.
In 614, Sui Yang-Emperor conscripted the armymen of the whole country to attack Koryu again. However, the people were against the war and the tyranny, and they rebelled one after another. Of course, Koryu were very weak after the wars of the two years. So when the army of Sui constrainedly arrived at the border, the Koryu’s king Yuan sent envoys to repatriate Hu Sizheng and ask for surrender. Sui Yang-Emperor dismembered Hu Sizheng and baked his flesh. The extremely atrocious emperor demanded the friends of Hu Sizheng to eat the flesh of Hu Sizheng. If a person didn’t eat, he would be regarded as the accessory of Hu Sizheng and he would be dismembered as Hu Sizheng. If a person ate much flesh, he would get official position and much largess. Sui Yang-Emperor demanded the king of Koryu to have an audience with him. But Yuan knew the emperor was extremely vicious, so he refused. Yang-Emperor was very angry, and ordered all armymen must prepare for the future war. However, the fire of rebellions was burning everywhere, and the Sui Empire had no chance to attack Koryu again.
The people of Koryu bitterly hated the Sui Dynasty, and they actually built a “Jingguan” (京观). “Jingguan” was a big tomb which buried all of the dead enemies, but the stele of the tomb showed the military achievements of the winners. So in fact, “Jingguan” was built for displaying military force of winners, but it was a serious disgrace to the enemy. The word “Jingguan” was from the Spring-Autumn Period of China. In 597 B.C., in the battle of Bi (邲), Jin (晋) State was defeated by Chu (楚) State, and many armymen died. A general of Chu suggested Chu Zhuang-King (楚庄王) to build a “Jingguan”, but Zhuang-King refused and said, “The 'Jingguan' is built for vicious criminals. However, these armymen were innocent, and all of them fought loyally for their own country. Can we built a 'Jingguan' for them?”
The invasive war started by Sui Yang-Emperor brought heavy suffering to both of Koryu's people and Chinese people. Many dynasties passed, the names of dead people were forgotten, and the cry of their parents, their wives and their children was forgotten, too.