South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korean Peninsula and lying to the east of the Asian mainland. The name Korea is derived from Goguryeo which was one of the great powers in East Asia during its time, ruling most of the Korean Peninsula, Manchuria, parts of the Russian Far East and Inner Mongolia, under Gwanggaeto the Great. South Korea lies in the north temperate zone and has a predominantly mountainous terrain. It comprises an estimated 51.4 million residents distributed over 100,363 km2. Its capital and largest city is Seoul, with a population of around 10 million.
Archaeology indicates that the Korean Peninsula was inhabited by early humans starting from the Lower Paleolithic period (2.6 Ma–300 Ka). The history of Korea begins with the foundation of Gojoseon in 2333 BCE by the mythic king Dangun, but no archaeological evidence and writing was found from this period. The Gija Joseon was purportedly founded in 11th century BCE, and its existence and role has been controversial in the modern era. The written historical record on Gojoseon (Old Joseon) was first mentioned in Chinese records in the early 7th century BCE. Following the unification of the Three Kingdoms of Korea under Unified Silla in CE 668, Korea was subsequently ruled by the Goryeo dynasty (918–1392) and the Joseon dynasty (1392–1910). It was annexed by the Empire of Japan in 1910. At the end of World War II, Korea was divided into Soviet and U.S. zones of occupations. A separate election was held in the U.S. zone in 1948 which led to the creation of the Republic of Korea (ROK), while the Democratic People's Republic of Korea (DPRK) was established in the Soviet zone. The United Nations at the time passed a resolution declaring the ROK to be the only lawful government in Korea.