The Three Kingdoms of Korea or Samhan (Goguryeo, Baekje and Silla) competed for hegemony over the Korean Peninsula during the ancient period of Korean history. During the Three Kingdoms period (), many states and statelets consolidated until, after Buyeo was annexed in 494 and Gaya was annexed in 562, only three remained on the Korean Peninsula: Goguryeo, Baekje and Silla. The "Korean Three Kingdoms" contributed to what would become Korea; and the Goguryeo, Baekje and Silla peoples became the Korean people.
The three kingdoms occupied the entire peninsula and roughly half of Manchuria (modern-day Northeast China and small parts of the Russian Far East). Goguryeo controlled the northern half of the peninsula, as well as Liaodong Peninsula and Manchuria. Baekje and Silla occupied the southern half of the peninsula. The island kingdoms of Tamna and Usan were subordinated to Baekje and Silla respectively.
All three kingdoms shared a similar culture and language. Baekje and Goguryeo shared founding myths which likely originated from Buyeo. Buddhism, which arrived in Korea in 3rd century AD from India via Tibet and China, became the state religion of all constituents of the three kingdoms, starting with Goguryeo in 372 AD. The Three Kingdoms of Korea all had a warrior aristocracy in contrast to the literary elite of China.
The period ended in the 7th century, after Silla allied with Tang China and unified the peninsula for the first time in history. After the fall of Baekje and Goguryeo, the Tang dynasty established a short-lived military government to administer parts of the Korean Peninsula. Silla was joined by Goguryeo and Baekje loyalists and fought the Tang for hegemony over the Korean Peninsula. Silla was eventually divided into the Later Three Kingdoms and ultimately annexed by the new Goguryeo revivalist state of Goryeo.
Nomenclature
Beginning in the 7th century, the name "Samhan" became synonymous with the Three Kingdoms of Korea. The "Han" in the names of the Korean Empire, Daehan Jeguk, and the Republic of Korea (South Korea), Daehan Minguk or Hanguk, are named in reference to the Three Kingdoms of Korea, not the ancient confederacies in the southern Korean Peninsula.
According to the Samguk sagi and Samguk yusa, Silla implemented a national policy, "Samhan Unification" (), to integrate Baekje and Goguryeo refugees. In 1982, a memorial stone dating to 686 was discovered in Cheongju with an inscription: "The Three Han were unified and the domain was expanded." During the Later Silla period, the concepts of Samhan as the ancient confederacies and the Three Kingdoms of Korea were merged. In a letter to an imperial tutor of the Tang dynasty, Choe Chiwon equated Byeonhan to Baekje, Jinhan to Silla, and Mahan to Goguryeo. By the Goryeo period, Samhan became a common name to refer to all of Korea. In his Ten Mandates to his descendants, Wang Geon declared that he had unified the Three Han (Samhan), referring to the Three Kingdoms of Korea. Samhan continued to be a common name for Korea during the Joseon period and was widely referenced in the Annals of the Joseon Dynasty.
In China, the Three Kingdoms of Korea were collectively called Samhan since the beginning of the 7th century. The use of the name Samhan to indicate the Three Kingdoms of Korea was widespread in the Tang dynasty. Goguryeo was alternately called Mahan by the Tang dynasty, as evidenced by a Tang document that called Goguryeo generals "Mahan leaders" () in 645. In 651, Emperor Gaozong of Tang sent a message to the king of Baekje referring to the Three Kingdoms of Korea as Samhan. Epitaphs of the Tang dynasty, including those belonging to Baekje, Goguryeo, and Silla refugees and migrants, called the Three Kingdoms of Korea "Samhan", especially Goguryeo. For example, the epitaph of Go Hyeon (), a Tang dynasty general of Goguryeo origin who died in 690, calls him a "Liaodong Samhan man" ().
The name "Three Kingdoms" was used in the titles of the Korean histories Samguk sagi (12th century) and Samguk yusa (13th century), and should not be confused with the Three Kingdoms of China.
Foundation
The Three Kingdoms were founded after the fall of Wiman Joseon and gradually conquered and absorbed various other small states and confederacies. After the fall of Gojoseon, the Han dynasty established four commanderies in the northwestern Korean Peninsula and present Liaoning. Three fell quickly to the Samhan, and the last was destroyed by Goguryeo in 313.