Korean Language Stack Exchange is a question and answer site for linguists, teachers and students of the Korean language. It only takes a minute to sign up.
Sign up to join this community
According to Wikipedia, the character 韓(한) used in 한국 and 대한민국 can also refer to:
(historical) Han, an ancient Chinese county, viscounty, and kingdom of the Zhou Dynasty and the Qin–Han interregnum.
But this seems to be a very different place, nowhere near Korea, around the area of modern-day Hanzhong.
Why does the same character refer to such different places?
The character 韓 for the name of Korea was arbitrarily chosen for its sound, coincidentally being the same character of some ancient Chinese states.
The first thing to point out is that there is rarely any Chinese character that was invented solely as a name for a people. Among the historical Chinese-character using countries and regions, their earliest recorded names are:
華夏 for Chinese:
) originally depicted vegetation, extended to mean flower, and was the original character for 花. Note that 華 and 花 are pronounced very similarly in Chinese and are pronounced identically in Korean (화). Flower was extended to mean flourish, prosper, then further extended to mean civilisation/China. Chinese today call themselves 華人.
) was originally comprised of 日 (sun) and either 頁 (head) or 見 (to see), depicting 'to raise one's head and see the sun', indicating something like hot weather and extended to mean summer. 日 was later cut off and the two dots on the bottom of 頁 became fully fledged feet (夂). Very early on the character was used for names of people, and was the name of the semi-mythical "first" dynasty of China, the Xia."Wa" for Japanese, first written 倭 and replaced with 和 later.
倭，順皃。从人，委聲。, thus a semanto-phonetic compound comprised of semantic 人 and phonetic 委). An anthropologically suitable explanation is that Wa came from Old Japanese わ (I, me), which matches the etymological origins of autonyms of many people around the world, and that 倭 is a phonetic loan for わ.
) depicts a kind of battle axe, and it is thought that the Chinese states to the north of the proto-Vietnamese states used this character to refer to their southern neighbours, the people of the Hundred Việt, as the latter were known for using and manufacturing these kinds of axes.The earliest name among ancient states that are now considered Korean is "Joseon" (조선), written as 朝鮮, and has been used for the majority of unified Korean history as the name of Korea; significantly, it is the name of the state of Gojoseon, the Joseon dynasty, and the current official name of North Korea, 朝鮮民主主義人民共和國. The name 조선 is of uncertain origin (some speculations are given here), but the characters definitely referred to other concepts first:
朝 (
) originally depicted the sun 日 rising through trees (木 or 屮) and meeting the moon (月) in the sky, indicating the meaning dawn/morning.
鮮 (
) was originally a graphical merger of sheep (羊) and fish (魚). Shuowen Jiezi explains it as "the name of a fish from 貉國 (a state in Northeastern China)" (鮮，魚名，出貉國。从魚，羴省聲。, thus a semanto-phonetic compound comprised of semantic 魚 and phonetic reduced from 羴).
"Han" (한) as a name of Korea was first attested as the three confederacies of Samhan, formed after Gojoseon's demise. It is a native Korean morpheme originally meaning great, speculated to be related to Turkic khan (as in Genghis Khan), and was variously written phonetically with 韓, 幹, 刊, 干, and even 漢. The name had nothing to do with various ancient Chinese states named 韓 or 漢.
韓 was originally 
(
). Shuowen Jiezi glosses it with the meaning fence surrounding a water well, and explains it as a semanto-phonetic compound comprised of the phonetic 倝 and semantic 韋, where 韋 means 'to surround' and is now written 圍 (as in 圍棋, the Chinese name for the board game 바둑). For reference, 韋 (
) originally depicted patrolling (feet 
, 
) around the outside of a city wall (wall 囗).
한국asKoreaoriginates from 고려 (Goryeo) which was propagated by foreign merchants visiting Korea during 918년~ 1392년.