The history of South Korea begins with the Japanese surrender on 2 September 1945. At that time, South Korea and North Korea were divided, despite being the same people and on the same peninsula. In 1950, the Korean War broke out. North Korea overran South Korea until US-led UN forces intervened. At the end of the war in 1953, the border between South and North remained largely similar. Tensions between the two sides continued. South Korea alternated between dictatorship and liberal democracy. It underwent substantial economic development.

The division of Korea began on August 15, 1945 when the official announcement of the surrender of Japan was released, thus ending the Pacific Theater of World War II. During the war, the Allied leaders had already been considering the question of Korea's future following Japan's eventual surrender in the war. The leaders reached an understanding that Korea would be liberated from Japan but would be placed under an international trusteeship until the Koreans would be deemed ready for self-rule. In the last days of the war, the United States proposed dividing the Korean peninsula into two occupation zones with the 38th parallel as the dividing line. The Soviets accepted their proposal and agreed to divide Korea.