Korea is a historical country in East Asia, since 1945 divided into two distinct sovereign states: North Korea (officially the "Democratic People's Republic of Korea") and South Korea (officially the "Republic of Korea"). Located on the Korean Peninsula, Korea is bordered by China to the northwest and Russia to the northeast. It is separated from Japan to the east by the Korea Strait and the Sea of Japan (East Sea). Korea emerged as a singular political entity after centuries of conflict among the Three Kingdoms of Korea, which were unified as Later Silla to the south and Balhae to the north. Later 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 Yuan Dynasty during the 13th century greatly weakened the nation, which eventually agreed to become a vassal state after decades of fighting. Following the Yuan Dynasty's collapse, severe political strife followed, and Goryeo eventually fell to a coup led by General Yi Seong-gye, who established Joseon in 1388. The first 200 years of Joseon were marked by relative peace and saw the creation of the Korean alphabet by Sejong the Great in the 14th century and the increasing influence of Confucianism. During the later part of the dynasty, however, 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 First Sino-Japanese War, despite attempts at modernization by the Korean Empire backed up by Japan, in 1910 Korea was annexed by Japan and remained a part of 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, with the North 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 incapability 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). This eventually led to the Korean War in 1950, which ended in a stalemate without a formalized peace treaty in 1953, a factor that contributes to the high tensions which continue to divide the peninsula. To date, both countries continue to compete with each other as the sole legitimate government of all of Korea.