|Baekje Kingdom||Entitled as Geummul-hyun, Imzon-seong, Osan-hyun|
|Silla Kingdom||Retitled as Geummu-hyun, Imseong-gun, Gosan-hyun|
|Goryeo Dynasty||Retitled as Deokpung-hyun, Daeheung-hyun, Yesan-gun|
|Joseon Dynasty||Retitled as Deoksan-gun, Daeheung-gun, Yesan-gun|
|1914. 01. 01||Integrated Yesan-gun, Daeheung-gun, Deoksan-gun into Yesan-gun by the Ministerial ordinance 111 (proclaimed on December 29, 1913) (12 myeons)|
|1940. 11. 01||Elavated Yesan-myeon to Yesan-eup by the Ministerial ordinance 221 (proclaimed on October 23, 1940) (1 eup 11 myeons)|
|1973. 07. 01||Elavated Sapgyo-myeon to Sapgyo-eup by the Presidential decree 6543 (proclaimed on March 12, 1973) (2 eups 10 myeons)|
|1983. 02. 15||Retitled parts of Hyorim-ri and Wolgok-ri to Wolsan-ri, and parts of Jwabang-ri as Bang-a-ri to be incorporated to Sapgyo-eup by the Presidential decree 11027 (proclaimed o February 15, 1983)|
It was originally Osan-hyun of Baekje Kingdom. Under the reign of the 35th king Gyeongdeok of Silla Kingdom, it became Gosan-hyun belonging to Imseong-gun and then was retitled to ‘Yesan’ in the second year (919) of Goryeo dynasty’s king Taejo.
In the 9th year of the 8th king Hyeonjong (1018), it was part of Cheonanbu and was later allowed a local official ‘Gammu’. This official title was promoted to Hyeongam in the 13th year of King Taejong of Choseon dynasty by rules to cover 9 myeons of Hyeonnae [Gunnae], Geumpyeong, Sulgok, Daejidong, Duchon, Ibam, Geoguhwa, Woogasan, and Owon-ri. In the reform of the local government organization in the 32nd year of the 26th king Gojong (1895) of Joseon dynasty, newly included Sinjong-myeon of Cheonan-gun. In 1914, the regions under its jurisdiction were reorganized to cover 12 myeons of Daesul, Eungbong, Oga, Sinam, Deoksan, Saphyo, Godeok, Bongsan, Daeheung, Gwangsi, Sinywang, and Yesan. The specific details are the followings: Deoksan-gun’s 11 myeons including Hyennae, Nabakso, Mt. Daedeoksan, Daejoji, Jangchon, Doyong, Gohyeonnae, and Oeya; Daeheung-gun’s eight myeons of Eumnae, Geun-dong, Illnam, Inam, Won-dong, Geobyeon, Naebuk, and Oebuk; Gongju-gun Sinsang-myeon’s five dongs or ris like Sanbuk, Yulgye, Duji, Bakun, Baekseok, Sincheon, and Hacheon; Sinchang-gun Namsang-myeon’s five dongs or ris of Deungdae, Gajeok, Daesojeong, Hyoja, and Bongam; Myeoncheon-gun Hapbuk-myeon’s two ris of Yeongsang and Yeongha; Bibang-myeon’s Donggot-ri and Masan-hyun’s Daegok-ri; Hongju-gun Namhado-myeon’s three ris of Guseong, Wonseong, and Garo; and Hongju-myeon’s Jung-ri, Biji of Chisa-myeon’s Chisa-dong, Jangjon-ri of Cheongyang-gun Seosang-myeon, and parts of Bukha-myeon’s Habuk-ri.
In 1917, Imseong-myeon was retitled to Yesan-myeon which was later elevated to Yesan-eup by the installation of the Eupjae system on October 1st, 1940. Currently, it consists of two eups, 10 myeons, and 175 dongs or ris, bordering Asan-si and Gongju-si to the east, Cheongyang-gun to the south, Hongseong-gun and Seosan-si to the west, and Dangjin-gun and Asan-si to the north
Although it was originally called Imjonseong or Geumju of Baekje Kingdom, King Gyeongdeok, the 35th king of Silla Kingdom, changed name to Imseong-gun.
In early period of Goryeo dynasty, the 9th year of the 8th king Hyeonjong, it was retitled to Daeheung belonging to Unju (運州 Hongseong) and allowed a local official Gammu in the 2nd year of the 19th king Myeongjong.
After elevated to gun in the 7th year of the 3rd king Taejong (1407), it was demoted to Hyeongam in his 13th year by rules. By celebrating King Hyeongjong’s family origin in Baksan of this village again in the 7th year of the 19th king Sukjong (1681), it was elevated to gun again and then demoted to hyun-gam later. The reform of local government organization in the 32nd year of the 26th king Gojong (1895) made it gun again and controlled eight myeons of Eumnae, Geobyeon, Won-dong, Geun-dong, Oebuk, Naebuk, Ilnam, and Inam. Incorporated into Yesan-gun in 1914 by the merger and abolition of the guns and myeons, it combined two myeons of Eupnae and Geun-dong into Daeheung-myeon, two myeons of Ilnam and Inam into Gwangsi-myeon, two myeons of Won-dong and Geobyeon into Sinyang-myeon, and two myeons of Naebuk and Oebuk into Bongsan(Eungbong)-myeon while containing parts of Oga-myeon.
It was originally called Geummul-hyun in Baekje Kingdom, that was later changed to Geummu under Isan-gun’s jurisdiction by the 25th king Gyeongdeok of Silla Kingdom. In the early period of Goryeo, 9th year of the 19th king Hyeonjong (1018), it was renamed as Deokpung and allowed a local official Gammu during the reign of the 19th king Myeongjong after subjected to Unju (運州:Hongseong). Baekje’s Masisan-gun became Isan-gun by Silla’s King Gyeongdeok, belonged to Unju during the 9th year of Goryeo’s King Heonjong, and later had a local official Gammu. In the 5th year of choseon’s 3rd king Taejong (1405), because of their few people and few natural resources, Isan and Deokpung were merged into Deoksan which was later allowed a local official Hyeon-gam by rules in the 13th year of the same king (1413). As a gun in the 13th year of the 24th king Heonjong (1847), it had control over 12 myeons of Jangchon, Daejoji, Mt. Daedeoksan, Nabakso, Hyeonnae, Naeya, Oeya, Doyong, Gohyeonnae, Gosan, Geodeung, and Bibanggot. In 1914, by the merger and abolition of guns and myeons, it was incorporated to Yesan-gun that covered Deoksan-myeon, Sapgyo-myeon, Godeok-myeon, Bongsan-myeon, and parts of Oga-myeon and Sinam-myeon. During the process, two myeons of Hyeonnae and Nabakso were merged into Deoksan-myeon, three myeons of Daedeoksan, Daejoji, Jangchon into Sapgyo-myeon, four myeons of Doyong, Gohyeonnae(parts), Geodong, and Gosan into Godeok-myeon, and two myeons of Naeya and Oeya as well as parts of Gohyeonnae were into Bongsan-myeon.