Korea is a region in East Asia. Since 1948, it has been divided between two distinct sovereign states: North Korea and South Korea. Located on the Korean Peninsula, Korea is bordered by China to the northwest, Russia to the northeast, and neighbours Japan to the east by the Korea Strait and the Sea of Japan (East Sea).
Korea emerged as a singular political entity in 676 AD, after centuries of conflict among the Three Kingdoms of Korea, which were unified as Unified Silla to the south and Balhae to the north. Unified Silla divided into three separate states during the Later Three Kingdoms period. Goryeo, which had succeeded Goguryeo, defeated the two other states and united the Korean Peninsula. Around the same time, Balhae collapsed and its last crown prince fled south to Goryeo. Goryeo (also spelled as Koryŏ), whose name developed into the modern exonym "Korea", was a highly cultured state that created the world's first metal movable type in 1234. However, multiple invasions by the Mongol Empire during the 13th century greatly weakened the nation, which eventually agreed to become a vassal state after decades of fighting. Following military resistance under King Gongmin which ended Mongol political influence in Goryeo, severe political strife followed, and Goryeo eventually fell to a coup led by General Yi Seong-gye, who established Joseon in 1392.
The first 200 years of Joseon were marked by relative peace. During this period, the Korean alphabet was created by Sejong the Great in the 15th century and there was increasing influence of Confucianism. During the later part of the dynasty, Korea's isolationist policy earned it the Western nickname of the "Hermit Kingdom". By the late 19th century, the country became the object of imperial design by the Empire of Japan. After the First Sino-Japanese War, despite the Korean Empire's effort to modernize, it was annexed by Japan in 1910 and ruled by Imperial Japan until the end of World War II in August 1945.
In 1945, the Soviet Union and the United States agreed on the surrender of Japanese forces in Korea in the aftermath of World War II, leaving Korea partitioned along the 38th parallel. The North was under Soviet occupation and the South under U.S. occupation. These circumstances 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 Communist-inspired government in the North received backing from the Soviet Union in opposition to the pro-Western government in the South, leading to Korea's division into two political entities: North Korea (formally the Democratic People's Republic of Korea), and South Korea (formally the Republic of Korea). Tensions between the two resulted in the outbreak of the Korean War in 1950. With involvement by foreign troops, the war ended in a stalemate in 1953, but without a formalized peace treaty. This status contributes to the high tensions that continue to divide the peninsula. Both governments of the two Koreas claim to be the sole legitimate government of the region.