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.
The Korean War began in June 1950 when forces from North Korea invaded South Korea. The war lasted three years and involved the U.S., China, the Soviet Union and several other nations. The border between the two nations remains the most heavily fortified in the world. Under long-time military leader Park Chung-hee, the South Korean economy grew significantly and the country was transformed into a G-20 major economy. Military rule ended in 1987, and the country is now a presidential republic consisting of 17 administrative divisions.
South Korea is a highly developed country and a high-income economy, with a "very high" Human Development Index, ranking 22nd in the world. The country is considered a regional power and is the world's 11th largest economy by nominal GDP and the 12th largest by PPP. South Korea is a global leader in the industrial and technological sectors, being the world's 5th largest exporter and 8th largest importer. Its export-driven economy primarily focuses production on electronics, automobiles, ships, machinery, petrochemicals and robotics. South Korea is a member of the ASEAN Plus mechanism, the United Nations, Uniting for Consensus, G20, the WTO and OECD and is a founding member of APEC and the East Asia Summit.
The name Korea derives from the name Goryeo. The name Goryeo itself was first used by the ancient kingdom of Goguryeo in the 5th century as a shortened form of its name. The 10th-century kingdom of Goryeo succeeded Goguryeo, and thus inherited its name, which was pronounced by the visiting Persian merchants as "Korea". The modern spelling of Korea first appeared in the late 17th century in the travel writings of the Dutch East India Company's Hendrick Hamel. Despite the coexistence of the spellings Corea and Korea in 19th century publications, some Koreans believe that Imperial Japan, around the time of the Japanese occupation, intentionally standardised the spelling on Korea, making Japan appear first alphabetically.
After Goryeo was replaced by Joseon in 1392, Joseon became the official name for the entire territory, though it was not universally accepted. The new official name has its origin in the ancient country of Gojoseon (Old Joseon). In 1897, the Joseon dynasty changed the official name of the country from Joseon to Daehan Jeguk (Korean Empire). The name Daehan, which means "Great Han" literally, derives from Samhan (Three Hans), referring to the Three Kingdoms of Korea, not the ancient confederacies in the southern Korean Peninsula. However, the name Joseon was still widely used by Koreans to refer to their country, though it was no longer the official name. Under Japanese rule, the two names Han and Joseon coexisted. There were several groups who fought for independence, the most notable being the Provisional Government of the Republic of Korea (대한민국 임시정부/大韓民國臨時政府).
Following the surrender of Japan, in 1945, the Republic of Korea (대한민국/大韓民國, IPA:, ; ) was adopted as the legal English name for the new country. Since the government only controlled the southern part of the Korean Peninsula, the informal term South Korea was coined, becoming increasingly common in the Western world. While South Koreans use Han (or Hanguk) to refer to the entire country, North Koreans and ethnic Koreans living in China and Japan use the term Joseon as the name of the country. The Korean name "Daehan Minguk" is sometimes used by South Koreans as a metonym to refer to the Korean ethnicity (or "race") as a whole, rather than just the South Korean state.