South Korea -- officially the Republic of Korea -- occupies the southern part of the Korean Peninsula.
Korea was a single country, ruled by the Japanese, until the end of World War II, when the north was occupied by the Soviet Union, and the south was occupied by the United States. These two were unable to reach an agreement and in 1950 the north attacked the south, starting the Korean War.
Today, the peninsula is cut in half by the Demilitarized Zone, a 248 km long by 4 km wide strip. While the north suffers from a dictatorship, the south is a democratic republic with an economy and a decent life for the people who live there.
South Korea on Wikipedia
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