This is believed to be because Jeollado's Jwasuyoung (Joseon Dynasty's Naval Headquarters for eastern sector of Jeolla Province) was established in this region starting in 1479 (the 10th year of King Seongjong's reign).

[8] The residential sites were constructed by compacting clay over shell layers, with diameters ranging from 460 to 540 centimeters, and featured a circular, flat layout equipped with round kilns.

[8] In 1992 and 1993, surface surveys were conducted in the islands of Yeosu, leading to the additional investigation of 22 Neolithic shell mounds and 3 artifact dispersal sites.

This revealed that the island regions of Yeosu, along with the coastal areas of South Gyeongsang Province, were cultural centers of the Neolithic period.

The site locations were predominantly situated in bays suitable for various shellfish habitats, being safe from sea winds and featuring well-developed shell pits.

The collected artifacts were similar to those unearthed from the Songdo shell mound, and a considerable number of Yunggimong pottery, which is dated to a relatively early period, were excavated.

In 538, Baekje moved its capital to Sabi-seong and divided the entire country into five regions (五方) centered around the central, eastern, western, southern, and northern areas.

In each region, Baekje established Bangseong (方城) and governed through these large and small fortresses, managing them as counties (郡) or prefectures (縣).

To manage the ruling elites of the conquered regions during the unification process, the provinces were divided into three sub-provinces each, forming a nine-province administration system.

Seungpyeong-gun (昇平郡) within Muju consisted of three hyeon (郡縣), maintaining the same names as in Baekje: Haeeup-hyeon (海邑縣, Yeosu), Yeosan-hyeon (廬山縣, Dolsan), and Heeyang-hyeon (晞陽縣, Gwangyang).

In 892 (the 6th year of Queen Jinseong's reign), during the chaotic end of the Unified Silla period, Gyeon Hwon established his kingdom with Mujinju as his base, thereby bringing it under the influence of Later Baekje.

[10][9] In 940 (the 23rd year of King Taejo's reign), the national administrative divisions were again reorganized into (주, ju),(부, bu),(군, gun), and (현, hyeon)-the addition of 부/bu.

These moksas were assigned to twelve provinces: Gwangju (廣州), Yangju, Chungju, Cheongju, Gongju, Jinju, Sangju, Jeonju, Naju, Hwangju, and Haeju.

Additionally, the twelve mok were transformed into twelve joldo-sa (절도사)s. The ten provinces were Gwannae (관내; 关内), Jungwon (중원; 中原), Hanan (하남; 河南), Gangnam (강남; 江南), Haeyang (해양; 海陽), Yeongnam (영남; 嶺南), Yeongdong (영동; 嶺東), Sannam (산남; 山南), Sakbang (삭방; 朔方), and Paeseo (패서; 浿西).

The Jeollanam-do region fell under Haeyang-do (海陽道), and Yeosu was governed by Seungju Joldo-sa (昇州節度使), overseeing Yeosu-hyeon (麗水縣) and Dolsan-hyeon (突山縣).

In 1018 (the 9th year of King Hyeonjong's reign), another reorganization took place, dividing the country into four Daedohobus(대도호부/大都護府), eight moks (8목; Gwangju, Chungju, Cheongju, Jinju, Sangju, Jeonju, Naju, Hwangju), fifty-six 'ji-gun-sa' s(56주지군사), twenty-eight 'jin-jang' s (28진장), and twenty 'hyun-young' s (20현령).

Additionally, during the Goryeo period, the Yeosu region included other areas such as Sam-ilpo-hyang, Jinrye-bugok, and Sora-po-bugok alongside Yeosu-hyeon and Dolsan-hyeon.

In the 142nd General Assembly of BIE, held in Paris on 26 November 2007, the global community selected Yeosu as the host city for the 2012 World Expo.