Short answers, pulled from the story.
The Korean Peninsula has been politically divided since the end of World War II in 1945. This division was established along the 38th parallel, separating the region into two distinct nations: the Democratic People's Republic of Korea in the north and the Republic of Korea in the south.
According to tradition, the kingdom of Gojoseon was founded in 2333 BC and fell to the Han dynasty in 108 BC. This event marked the beginning of a long history of interaction with Chinese dynasties.
The world's first metal movable type was invented by Ch'oe Yun-üi in 1234 CE. This invention made printing easier and more efficient, increasing literacy and allowing the Mongol Empire to adopt the technology and spread it to Central Asia.
The Japanese invaded Korea in 1592 and again in 1597, causing great destruction and the loss of cultural sites such as temples and palaces. The Korean military was defeated by strong resistance from the Righteous Army, the naval superiority of Admiral Yi Sun-sin, and assistance from the Wanli Emperor of Ming China.
Korea became a protectorate of Japan shortly after the conclusion of the Russo-Japanese War in 1905. The country was forced to sign the Japan, Korea Annexation Treaty in 1910, which remains a subject of legal dispute due to its signing under duress.
During the Korean War from 1950 to 1953, more than 1.2 million people died. The three years of fighting throughout the nation effectively destroyed most cities and ended with an armistice agreement at approximately the Military Demarcation Line.