The history of Korea stretches from Lower Paleolithic times to the present. The earliest known Korean pottery dates to around 8000 BCE, and the Neolithic period began before 6000 BCE, followed by the Bronze Age around 2500 BCE. The Gojoseon (Old Joseon) kingdom was founded in 2333 BCE, eventually stretching from the peninsula to much of Manchuria. By 3rd Century BCE, it disintegrated into many successor states.

In the early Common Era, the Three Kingdoms (Goguryeo, Silla, and Baekje) conquered other successor states of Gojoseon and came to dominate the peninsula and much of Manchuria. The three kingdoms competed with each other both economically and militarily. While Goguryeo and Baekje were more powerful for much of the era (especially Goguryeo, which defeated massive Chinese invasions) Silla's power gradually extended across Korea and it eventually established the first unified state to cover most of Korean peninsula by 676, while former Goguryeo general Dae Jo-yeong founded Balhae as the successor to Goguryeo.

Unified Silla itself fell apart in the late 9th century, giving way to the tumultuous Later Three Kingdoms period (892-936), which ended with the establishment of the Goryeo Dynasty. After the fall of Balhae in 926 to Khitan, much of its people led by the Crown Prince Dae Gwang-hyeon were absorbed into Goryeo. During the Goryeo period, laws were codified, a civil service system was introduced, and Buddhism flourished. In 993 - 1019 Khitan Liao Dynasty invaded Goryeo and were repelled. In 1238, the Mongolian Empire invaded and after nearly thirty years of war, the two sides signed a peace treaty.

In 1392, the general Yi Seong-gye established the Joseon Dynasty (1392-1910) after a coup. King Sejong the Great (1418-1450) promulgated hangul, the Korean alphabet. Between 1592-1598, Japan invaded Korea, but was eventually repelled with the efforts by the Navy led by Admiral Yi Sun-sin, resistance armies, and Chinese aid. In the 1620s and 1630s, Joseon suffered invasions by the Manchu Qing Dynasty.

Beginning in the 1870s, Japan began to force Korea out of China's sphere of influence into its own. In 1895, Empress Myeongseong of Korea was assassinated by Japanese agents. In 1905, Japan forced Korea to sign the Eulsa Treaty making Korea a protectorate, and in 1910 annexed Korea, although neither is considered to be legally valid. Korean resistance to the Japanese occupation was manifested in the massive nonviolent March 1st Movement of 1919. Thereafter the Korean liberation movement, coordinated by the Provisional Government of the Republic of Korea in exile, was largely active in neighboring Manchuria, China and Siberia.

With the defeat of Japan in 1945, the United Nations developed plans for a trusteeship administration by the Soviet Union and the United States, but the plan was soon abandoned. In 1948, new governments were established, the democratic South Korea and Communist North Korea divided at the 38th parallel. The unresolved tensions of the division surfaced in the Korean war of 1950, when North Korea invaded South Korea.