Sam (三) means "three", and Han is a Korean word meaning "great" or "leader." Han was transliterated into Chinese characters 韓, 幹, or 刊, but is unrelated with the Han in Han Chinese and the Chinese kingdoms and dynasties also called Han (漢, 韓). The names of these confederacies are reflected in the current name of South Korea, Daehan Minguk (literally, "Great Han People's Nation"). See Names of Korea.
The Samhan are thought to have formed around the time of the fall of Gojoseon in northern Korea in 108 BC, around when the state of Jin in southern Korea also disappears from written records. By the fourth century, Mahan was fully absorbed into the Baekje kingdom, Jinhan into the Silla kingdom, and Byeonhan into the Gaya confederacy, which was later annexed by Silla.
The Samhan are generally considered loose confederations of walled-town states. Each appears to have had a ruling elite, whose power was a mix of politics and shamanism. Although each state appears to have had its own ruler, there is no evidence of systematic succession.
The name of the poorly understood Jin state continued to be used in the name of the Jinhan confederacy and in the name "Byeonjin," an alternate term for Byeonhan. In addition, for some time the leader of Mahan continued to call himself the King of Jin, asserting nominal overlordship over all of the Samhan confederations.
Mahan was the largest and earliest developed of the three confederacies. It consisted of 54 minor statelets, one of which conquered or absorbed the others and became the center of the Baekje Kingdom. Mahan is usually considered to have been located in the southwest of the Korean peninsula, covering Jeolla, Chungcheong, and portions of Gyeonggi.
Jinhan consisted of 12 statelets, one of which conquered or absorbed the others and became the center of the Silla Kingdom. It is usually considered to have been located to the east of the Nakdong River valley.
Byeonhan consisted of 12 statelets, which later gave rise to the Gaya confederacy, subsequently annexed by Silla. It is usually considered to have been located in the south and west of the Nakdong River valley.
Villages were usually constructed deep in high mountain valleys, where they were relatively secure from attack. Mountain fortresses were also often constructed as places of refuge during war. The minor states which made up the federations are usually considered to have covered about as much land as a modern-day myeon, or township.
Based on historical and archeological records, river and sea routes appear to have been the primary means of long-distance transportation and trade (Yi, 2001, p. 246). It is thus not surprising that Jinhan and Byeonhan, with their coastal and river locations, became particularly prominent in international trade during this time.
The introduction of iron technology also facilitated growth in agriculture, as iron tools made the clearing and cultivation of land much easier. It appears that at this time the modern-day Jeolla area emerged as a center of rice production (Kim, 1974).
In the beginning, the relationship was tributary: a political trading system in which "tribute" was exchanged for titles or prestige gifts. Official seals identified each tribal leader's authority to trade with the commandery. However, after the fall of the Kingdom of Wei in the third century, San guo zhi reports that the Lelang commandery handed out official seals freely to local commoners, no longer symbolizing political authority (Yi, 2001, p. 245).
The Chinese commanderies also supplied luxury goods and consumed local products. Han dynasty coins and beads are found throughout the Korean peninsula. These were exchanged for local iron or raw silk. After the second century CE, as Chinese influence waned, iron ingots came into use as currency for the trade based around Jinhan and Byeonhan.
Trade relations also existed with the emergent states of Japan at this time, most commonly involving the exchange of ornamental Japanese bronzeware for Korean iron. These trade relations shifted in the third century, when the Yamatai federation of Kyūshū gained monopolistic control over Japanese trade with Byeonhan.
In the late Joseon period, that historical notion came under criticism by an early Silhak scholar, Han Baek-gyeom who emphasized the linkage between Mahan and Baekje in terms of the geographical location.