North Korea
Between 1910 and the end of World War II in 1945, Korea was considered a part of Japan due to Japan's colonization of Korea. In 1945, the USSR declared war on Japan and the United States bombed it (Nagasaki and Hiroshima); severely weakening its empire and forcing Japan to surrender. Japan's weak status allowed the Soviets to enter Korea fairly, freely and occupy the northern half whilst the United States took the southern half. The line that splits North Korea and South Korea is called the 38th parallel. Each created governments supporting their own ideologies, Marxist–Leninist Single Party State (North) and Democratic Capitalist State (South).