Ethnic groups
It was long believed that the Korean people originally may have had links with the people of Central Asia, the Lake Baikal region of Siberia, Mongolia, and the coastal areas of the Yellow Sea. Tools of Paleolithic type and other artifacts found in Sokchang, near Gongju, are quite similar to those of the Lake Baikal and Mongolian areas. In 2017, genetic analysis of bones found in Primorye kray in Far Eastern Russia suggested that Koreans were related to a population that had inhabited that area for at least 7,700 years. The genes of these Neolithic humans were expressed alongside those of Indigenous agriculturalists from Southeast Asia to produce the genetic structure of modern Koreans.
The population of South Korea is highly homogeneous; almost the entire population is ethnically Korean, and there is a small minority of ethnic Chinese permanent residents. The number of foreigners is growing, especially in the major urban areas; people from Japan, the United States (including members of the military), and China make up the largest foreign populations, although they still constitute only small fractions. Many foreign nationals are employed in business or the diplomatic corps, and tens of thousands of workers come from China and Southeast Asia.
Religion
Freedom of religion is constitutionally guaranteed in South Korea, and there is no national religion. There also is little uniformity of religious belief, a situation that often is confusing to outside observers. Historically, several religions prevailed successively: shamanism (the religious belief in gods, demons, and ancestral spirits responsive to a priest, or shaman), Buddhism, Daoism, and Confucianism. None of these religions was abandoned, however, when one supplanted another in dominance, and all have had a role in the country’s sociocultural development. Thus, the rites of shamanism (which has existed in Korea since ancient times) are still practiced by many. The principles and social outlook of Confucianism are still much in evidence in Korean daily life and family relationships, and Buddhism remains influential—even among people who may be nominally Christian, for example. Approximately one-fourth of the population professes Christianity, with Protestants (particularly Presbyterians and Methodists), independent Christians, and Roman Catholics the largest groups. Less than one-sixth of the population is Buddhist.
Christianity is relatively new in Korea, Roman Catholic missionaries having reached the peninsula only in the late 18th century and their Protestant counterparts a century later. Christianity has had a profound effect on the modernization of Korean society. Buddhism was first introduced in the 4th century ce and was the official religion of the Goryeo dynasty, which began in 918. About one-sixth of the population adheres to so-called new religions. These include Wonbulgyo (Won Buddhism), Daejonggyo (“Great Ancestral Religion”), and Cheondogyo. Cheondogyo (“Teaching of the Heavenly Way”), originally known as Donghak (“Eastern Learning”), is a blend of Buddhism, Confucianism, Christianity, and even Daoism; it spread widely in the latter part of the 19th century. Shamanism and traditional geomancy (pungsu) persist, though their practices usually are limited to certain occasions, such as funerals. Confucianism was the basis of national ethics during the Joseon (Yi) dynasty (1392–1910); though the number of its official adherents is now small, most Korean families still follow its principles, including ancestor worship.