There is archaeological evidence that people were living on the Korean peninsula 700,000 years ago. The Palaeolithic period began around 70,000 BC, and earliest known Korean pottery dates to around 7000 BC, and the Neolithic period begins around 6000 BC.
Eventually (2333 BC according to the Dangun legend), Gojoseon was founded, encompassing northern Korea and Manchuria. In 108 BC, Gojoseon fell to the Chinese Han dynasty, who installed four commanderies in northern Korea, three of which quickly fell to Korean resistance. In this period, southern Korea was occupied first by the Jin state, and later the Samhan, three loose confederacies.
In the north, the expanding Goguryeo reunited Buyeo, Okjeo, and Dongye in the former Gojoseon territory, and destroyed the last Chinese commandery in 313.
The three kingdoms Goguryeo, Silla, and Baekje (the latter two arising from the Samhan) competed with each other as minor statelets fell or merged with these regional powers. Sophisticated state organizations developed under Confucian and Buddhist paradigms. Goguryeo was the most dominant power, but was at constant war with the Chinese Sui and Tang. Emperor Yang-ti of Sui, with one million troops, invaded Goguryeo, but in 612 CE, General Eulji Mundeok pushed the Chinese force into retreat. The Sui fall from power in China was partly due to Goguryeo.
Silla was the least advanced of the Three Kingdoms, but had established a fierce military. Silla first annexed Gaya, then conquered Baekje and Goguryeo with Tang assistance. Silla warriors were called the Hwarang.
Silla eventually repulsed Tang from Goguryeo territory, although the northern part regrouped as Balhae. Silla ("Unified Silla" hereon) thus came to control most of the Korean peninsula by the 8th century. In the late 9th century, Unified Silla gave way to the brief Later Three Kingdoms period.
After the fall of Goguryeo, General Dae Joyeong led a group of his people to the Jilin area in Manchuria. The general founded the state of Balhae (Bohai in Chinese) as the successor to Goguryeo and regained control of lost northern territory. Eventually, Balhae's territory would extend from the Sungari and Amur Rivers in northern Manchuria all the way down to the northern provinces of modern Korea. In the 10th century Balhae was conquered by the Khitans.
The kingdom of Goryeo (918 CE–1392 CE) replaced Silla as the dominant power in Korea. Many members of the Balhae ruling class joined the newly founded Goryeo Dynasty, which established boundaries of Korea to a little more than where they exist today (See Gando region which is now occupied by the Chinese). During this period, laws were codified, and a civil service system was introduced. Buddhism flourished throughout the peninsula.
In the 10th and 11th centuries, Goryeo continued to be plagued by attacks from Jurchen and Khitan tribes on the northern borders. Conflict increased between civil and military officials in Goryeo as the latter were degraded and poorly paid. This led to an uprising by military and forced some military officials to migrate to other areas. In 1238 the Mongols invaded Goryeo and laid the kingdom in ruins as resistance continued on and off for almost thirty years. Eventually, a treaty was signed between the two kingdoms in favor of the Mongols. In the 1340s, the Mongol Empire declined rapidly due to internal struggles. Korea was at last able to forge political reform with out mongol interference. At this time a General named Yi Seong-gye distinguishes himself by repelling Japanese pirates who were constantly stealing mainland technology from Korean and Chinese merchant ships.
In 1392 Yi Seong-gye established the Joseon Dynasty, moving the capital to Hanseong (now Seoul). Hangul was created by King Sejong in 1443. During the late 1500s, Japan invaded Korea in two failed attempts, known together as the Seven-Year War, inflicting great destruction and suffering on Korea. The Manchus then successfully invaded China and forced Korea in 1627 to recognize the Manchu government.
Beginning in the 1870s, Japan began to acquire western technology then forced Korea away from China's sphere of influence. In 1895, Empress Min of Korea was murdered by the Japanese under Miura Goro. Japan further increased its control over Korea following the First Sino-Japanese War (1894) and the Russo-Japanese War (1904–1905).
In 1910, Korea was annexed by Japan. Japanese occupation lasted until 1945 when Japan was defeated by the Allied Forces at the end of World War II.
Many Koreans were forcibly sent all around the empire, men as slave laborers and women as military sex slaves called "comfort women". During the suppression of independence movement in 1919, 7,000 Koreans were killed by Japanese police and soldiers. Although statistics are difficult to obtain and verify, around 60,000 Korean laborers in Japan are known to have died between 1939 and 1945. Anti-Japanese sentiment still runs strong in Korea , as a result of Japanese war crimes and what Koreans see as continuing unrepentant actions.
In 1945, in the aftermath of WWII, the United Nations developed plans for a trusteeship administration, the United States effectively began administering the peninsula south of the 38th parallel and the Soviet Union administering north. The politics of the Cold War resulted in the 1948 establishment of two separate governments.
In June 1950, North Korea invaded the South, beginning the Korean War. After three devastating years of fighting that involved China, Soviet Union, the US, and several United Nations countries (including Canada, Great Britain, and Turkey to name a few), the war ended in a ceasefire agreement at approximately the same boundary. The two countries never signed a peace treaty.
Since the 1990s, with progressively liberal South Korean administrations, as well as the death of North Korean founder Kim Il-sung, the two sides have taken halting, symbolic steps towards cooperation, in international sporting events, reunification of separated family members, and tourism.