Some of the most important changes in Korean history happened after World War II.  

Of course, a major change was that Korea became independent.  Importantly, it did not do so as one country.  Instead, it became North Korea and South Korea.  We will look here at South Korea and its political system.

After independence, South Korea came to be dominated by Syngman Rhee. The country was officially a republic, but Rhee essentially ruled as an autocrat.  This situation came to an end in 1960 when Rhee was forced to resign by widespread protests.  This brought in a period of more vigorous political activity.  This was a fairly democratic time, but it was chaotic.  This led to a coup in 1961 in which Park Chung-hee became military ruler of South Korea.  Park was assassinated in 1979, but the military rule continued.  This lasted until 1987 when a much more democratic system emerged.