Which country or place do you think of when you hear “Koreans’ living area”? Many people tend to thing of South Korea or North Korea, the nation from the Korean Peninsula. However, as a matter of fact, Koreans are separated all around the world, establishing their own society in various places. In this lecture, we will analyze the main factor of defining an ethnic group, “the use of language”, in order to understand the characteristics of Koreans’ living areas all around the world.