Jeju-do
In the middle of the 20th century, the Korean War divided Korea into two countries, North Korea and South Korea.  In 1948, there was an uprising on Jeju Island.   The government of what would become South Korea burned down most of the villages on Jeju Island and killed 30,000 people.  People disagree about exactly what happened and why.  Some people say the government was trying to stop Communists and other people say the Jeju Islanders who were killed were rebels who didn't want the country cut into two pieces.  In 2003, the government of South Korea apologized.