Since the Sui Dynasty, Koguryo (高句丽) had been called Koryu (高丽), and its capital had been Pyongyang (平壤). Sui Yang-Emperor (隋炀帝) started several wars against Koryu, but the Sui Empire couldn’t capture this strong country. The last straw of the fateful rebellion which was against the Sui Empire was the war of Koryu.
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.
When we talk about the ancient relations between the Tang Dynasty of China and Japan, we can remember how close and friendly the relationship of two nations was. However, maybe many people don’t know, in the early days of the Tang Dynasty there was a battle between the two nations, and Chinese army fought against Japanese army for the first time.
Since the Southern Dynasties of ancient China, Japanese eagerly studied the advanced culture and technology from the Chinese nation. Japanese was called “Wo” (倭) by Chinese. Japanese kings paid tributes to the emperors of China every year, and the emperors conferred titles on them. The Japanese nation was a clever people, and they were eager to excel other nations. When they comprehended the culture of the Chinese nation, they found the name and status of their nation were not well. So Japanese wanted to show their self-respect to the Central Nation.
Between China and Japan, there has been a complicated relationship. The two countries in the East Asia sometimes were hand-in-hand friends and sometimes were absolutely irreconcilable opponents. In the friendly years, the people from the two nations often agreeably talked about the long history of the two nations’ friendship. In the hostile years, the people from the two nations were often involved in furious conflicts around the war history. Conflicts often cause extremism, and the exchanges of thoughts always promote common understanding.
Here the "Korean War" was the war that the Han army captured Joseon (朝鲜). This Joseon was a country which was built by Wei Man (卫满) in modern-day Northern Korea. In the later days of the Warring-State Period, the former Joseon submitted itself to the Yan (燕) State. When the Qin (秦) State annexed the Yan State, the army of Qin entered Joseon and captured it. In the early days of the Western Han Dynasty, the imperial government abandoned Joseon because the government thought Joseon was very remote and this land couldn’t be guarded easily.