Since the Goryeo Dynasty, Korea was ruled by a single government and maintained political and cultural independence until the 20th century, despite the Mongol invasions of the Goryeo Dynasty in the 13th century and Japanese invasions of the Joseon Dynasty in the 16th century. In 1377, Korea produced the Jikji, the world's oldest existing document printed with movable metal type. In the 16th century, the turtle ships were deployed, and King Sejong the Great promulgated the Korean alphabet, Hangul.
During the latter part of the Joseon Dynasty, Korea's isolationist policy earned it the Western nickname the "Hermit Kingdom". By the late 19th century, the country became the object of the colonial designs of Japan and Europe. In 1910, Korea was forcibly annexed by Japan and remained occupied until the end of World War II in August 1945.
In 1945, the Soviet Union and the United States agreed on the surrender and disarming of Japanese troops in Korea; the Soviet Union accepting the surrender of Japanese weaponry north of the 38th parallel and the United States taking the surrender south of it. This minor decision by allied armies soon became the basis for the division of Korea by the two superpowers, exacerbated by their inability to agree on the terms of Korean independence. The two Cold War rivals then established governments sympathetic to their own ideologies, leading to Korea's current division into two political entities: North Korea and South Korea.