三韩是公元前2世纪末至公元后4世纪左右朝鲜半岛南部三个部落联盟，包括马韩，辰韩和弁韩。 其中马韩是三韩中最强大的，被三韩拥立为“辰王”，定都目支国，统领三韩之地。4世纪马韩已被百济兼并。辰韩被新罗兼并，弁韩则演化成伽倻后又被新罗兼并。

“三韩”一词最早在中国的典籍《后汉书·东夷列传》中出现。三韩所在的具体位置存在争议。不同时期，三韩的边界也不断的变化。但大体上认为在朝鲜半岛的南部，大致为今天的大韩民国。《后汉书》曰三韩之地“皆古之辰国也”

「韩」（韩语：한）在现代韩语中被赋予“伟大”或“领袖”的意思。大韩民国的国名中就含有“韩”字。「韩」后来演变为朝鲜族的别名。三韩是现在朝鲜族的直系祖先，也是如今韩国国名得来的原因。

The Samhan period of Korean history (also Proto-Three Kingdoms of Korea) comprises confederacies of Mahan, Jinhan, and Byeonhan in central and southern Korean peninsula, during the final century BCE and the early centuries CE. These confederacies were eventually absorbed into two of the Three Kingdoms of Korea by the 4th century CE. The Samhan period is generally considered a subdivision of the Three Kingdoms Period.