History of South Korea
On August 15, 1948, the Republic of Korea was formally established, with Rhee Syngman as the first president. With the establishment of Rhee's government, de jure sovereignty also passed into the new government. On September 9, 1948, a communist regime, the Democratic People's Republic of Korea (North Korea), was proclaimed under Kim Il-sung. However, on December 12, 1948, by its resolution 195 in the Third General Assembly, the United Nations recognized the Republic of Korea as the sole legal government of Korea.
South Korea
Following the surrender of Japan, in 1945, the "Republic of Korea" (/, 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.