Korea is a land in East Asia that occupies a peninsula extending south from northeastern China. For hundreds of years, Korea existed as a single state, ruled by various Korean and foreign governments. Today, two countries occupy the Korean Peninsula. One is the Democratic People’s Republic of Korea—commonly called North Korea. It has a Communist government, and its Communist Party holds political power. The other is the Republic of Korea—usually called South Korea. It has a democratically elected government.
Plains stretch along the western, northeastern, and southern coasts of Korea. Mountains cover most of the rest of the peninsula. Almost all inhabitants of both North and South Korea are ethnic Koreans. Most of them live on the coastal plains or in river valleys.
People probably have lived in what is now Korea for at least 30,000 years. In A.D. 668, three separate kingdoms on the Korean Peninsula united into a single kingdom. From 668 to the 1900’s, various Korean dynasties (families of rulers) held power in Korea. During that time, there were also periods of invasion and occupation by the Chinese, Mongols, and Japanese. In 1910, Korea became a colony of Japan. After Japan’s defeat in World War II in 1945, Korea gained freedom from Japan but became divided. Forces from the Soviet Union occupied the northern part of the peninsula, and United States forces occupied the southern part. The separate governments of South Korea and North Korea were formed in 1948. 
In 1950, North Korean troops invaded South Korea. This action started the Korean War, which lasted until 1953. Neither side won a complete victory, and a permanent peace treaty has never been signed.
From time to time, discussions have taken place between the two countries about reunifying Korea. But tensions between the North and South and among powerful countries interested in Korea have prevented reunification. For more complete information about the history of Korea and the modern states of North and South Korea, see Korea, North ; Korea, South ; Korean War .
