Korea is located in Eastern Asia, the northern half of the Korean Peninsula borders the Korea Bay and the Sea of Japan. The southern half of the Korean Peninsula borders the Sea of Japan and the Yellow Sea. Korea was first populated by people who migrated to the peninsula from the northwestern regions of Asia, some of whom also settled parts of northeast China (Manchuria). Koreans are racially and linguistically homogeneous, with no sizable indigenous minorities, except for some Chinese (approximately 20,000).
South Korea's major population centers are in the northwest area and in the fertile plain to the south of Seoul-Inchon. The mountainous central and eastern areas are sparsely inhabited. The Japanese colonial administration of 1910-45 concentrated its industrial development efforts in the comparatively under-populated and resource-rich north, resulting in a considerable migration of people to the north from the southern agrarian provinces. This trend was reversed after World War II as Koreans returned to the south from Japan and Manchuria. In addition, more than 2 million Koreans moved to the south from the north following the division of the peninsula into U.S. and Soviet military zones of administration in 1945. This migration continued after the Republic of Korea was established in 1948 and during the Korean War (1950-53).
South Korea has one of the world's highest population densities--much higher, for example, than India or Japan--while the territorially larger North Korea has only about 22 million people. Ethnic Koreans now residing in other countries live mostly in China (1.9 million), the United States (1.52 million), Japan (681,000), and the countries of the former Soviet Union (450,000).
Korea's traditional religions are Buddhism and Shamanism. Buddhism has lost some influence over the years, but is still followed by about 27% of the population. Shamanism--traditional spirit worship--is still practiced. Confucianism remains a dominant cultural influence. Since the Japanese occupation, it has existed more as a shared base than as a separate philosophical/religious school. Some sources place the number of adherents of Chondogyo--a native religion founded in the mid-19th century that fuses elements of Confucianism and Christianity--at more than 1 million.