Archaeological evidence indicates that the Korean Peninsula was inhabited by lower Palaeolithic people at least as early as 500,000 B.C. Many archaeological sites, mostly located along rivers, have been excavated. The most famous are Seokjang-ri in Chungcheongnam-do province and Jeon-gok-ri in Gyeonggi-do province. Various stone tools, including hand-axes and chopper-scrapers, have been found at these sites, leading archaeologists to believe that their inhabitants engaged in hunting and fishing. These people are thought to have dwelt in caves, as the bones of many extinct animals and relics of their daily life have been unearthed. The supposed connection between these palaeolithic peoples and today's Koreans is blurred by the lack of sufficient archaeological excavations and anthropological evidence.

Scholars generally agree that the ancestors of today's Koreans were late-comers of the Neolithic Period. According to anthropological and linguistic studies, as well as legendary sources, Koreans trace their ethnic origins to people who lived in and around the Altaic mountains in Central Asia. Several thousand years ago, these people began to migrate eastward until they finally settled in an area that included Manchuria and the Korean Peninsula.

When these migrants entered the Korean Peninsula around the third millennium B.C., they were confronted by natives called Paleoasians, who were eventually driven into various areas outside the Korean Peninsula. The Ainu of the northern tip of Japan, the natives of Sakhalin and the Eskimos of the eastern coast of Siberia are all descendants of these Paleoasian tribes.

Archaeological studies have uncovered two different types of pottery of this period, which raises the possibility that the inhabitants of the Korean Peninsula belonged to two very different cultural eras. For example, two distinctly different kinds of pottery have been discovered: the comb pattern pottery of a Neolithic Age people and the plain pottery of a Bronze Age people. The patterned pottery, believed to be the product of a food-gathering, hunting and fishing people, has been discovered near river banks and along the seashore, while the plain pottery, believed to have come from a food-producing people, has been unearthed mostly in the hilly regions of the country. Although these two peoples appear to have possessed different technologies, they shared the same culture, distinct from the Han Chinese.

As noted, most of the natives were subsequently driven north to Sakhalin, Kamchatka, and to the Arctic region by these newcomers, while a few were assimilated. Some of the migrants continued to move and eventually reached the southwestern shores of Japan. As a result, cultural similarities, such as belief systems (for example, shamanism, myths and customs) as well as shared physical traits among the ancient Koreans, Japanese and Siberian Eskimos still exist.

Agriculture was introduced during the Bronze Age, which began around the 15th century B.C. Increased food production and population growth led to social differentiation based on unequal access to economic resources on one hand, and clan or kin group formations on the other. Tribal societies of various sizes were established on the basis of clan relations, with some established chiefdoms and mini-states that competed with each other. At the same time, people continued to migrate to Japan. Possessing more advanced civilization and culture, these migrants enjoyed ruling class status and eventually established their own small mini-states in the archipelago. The southwestern part of Japan, in particular, offered easy access to culture from the Korean Peninsula. This region provides ample archaeological evidence of significant cultural and ethnic relations with Korea. More archaeological study is required to draw an exact map showing how widely the people who are now called Koreans were dispersed during this period. Based on Chinese records and archaeological reports, however, it is assumed that they were living not only on the Korean Peninsula but also in the vast areas of Manchuria and the region along the lower Yellow River basin of the Shandong Peninsula in China.

Cultural contact with the Chinese also was significant. Around the 4th century B.C., iron making was introduced through contacts with the Chinese. Intertribal competition as well as interethnic contact with the Chinese became more frequent. The numerous Korean mini-states and tribal groups banded together into several leading states, to resist Chinese military expansion. Since the Age of Three Kingdoms, namely Silla, Baekje and Goguryeo, a strong sense of ethnic identity and cultural distinctiveness was maintained.

During the latter half of the 7th century, the Silla Kingdom unified the three states, a significant event because this political unity was to consolidate the homogeneity of the Korean people who now began to speak one language and share the same culture.

However, the northern half of the Korean Peninsula and the whole of Manchuria, which had been the territory of Goguryeo, came under the reign of a new state called Balhae, established by a refugee group from the defeated Goguryeo. This state was highly heterogeneous both ethnically and culturally. The ruling class was composed exclusively of Koreans, while the general public was made up of various non-Korean local ethnic groups including the Manchurian Tungus. The ruling Koreans failed to incorporate the non-Koreans, and as a result, their state was challenged and gave way to the largest of the native ethnic groups. From that time onward, Manchuria was inhabited by various groups of Tungusic people.

While there was a considerable mixing of races among the various peoples in Manchuria, the inhabitants of the Korean Peninsula preserved their ethnic identity with only minimal mixing with external groups. Although cultural contacts were extensive between Korea and China from the early stages of their history, ethnic assimilation did not occur. Koreans were (and still are) highly conscious of ethnic differences and cultural distinctions, which meant safeguarding their ethnic identity despite relations with China and Japan. Koreans exported their own culture and transmitted Chinese culture to Japan from ancient times, but they did not attempt to engage in any ethnic mixing with the Japanese. Many ethnic groups in Manchuria lost most of their ethnic identity and were even completely assimilated with dominant groups; Koreans, however, have kept their ethnic identity and culture intact.

There are, at present, over 1 million Koreans residing in the United States; more than 600,000 currently reside in Japan. Approximately half a million ethnic Koreans now live in Central Asia, while more than 2 million Koreans reside in the vast areas of Manchuria. Despite their minority status in their respective communities, however, Koreans abroad have maintained their ethnic and cultural identity, using their own language and continuing their own traditional social institutions and lifestyles.

According to a 1995 Sports Indicators of Korea published by Korea Sport Science Institute, the average height of a modern Korean, ages 25-29, is 172.5 centimeters for men and 158.8 centimeters for women. In terms of height, this means that Korean males belong to the upper middle scale and Korean females to the medium scale, compared to other Asian people. Their most distinctive physical features are almond-shaped eyes, black hair and relatively high cheek bones. It may also be noted that all Korean babies are born with blue spots on the lower part of the back, which is also typical of Mongolians.