고려시대 전라도 서남해상 도서에는 7곳의 군현이 설치되었는데, 진도 3현은 진도, 압해군과 장산․임치․육창 3현은 각각 압해도와 나주군도의 중앙부, 나주군도의 남부, 임자군도, 나주군도의 북부에 위치하였다. 지도는 육지의 해제현 소속이었으며, 흑산도에는 군현이 설치되지 않았다. 1018년 서남해상의 7군현 중 진도 3현과 압해군, 장산현은 나주의 속군현이, 육창․임치 2현은 영광군의 속현이 되었다. 1143년에는 7군현 중 진도현에는 외관이 파견되었고, 가흥․임회 2현은 진도현의 속현이 되었으며, 압해군은 나주에서 영광으로 이속되었다.
고려말 왜구의 침입으로 인해 서남해상의 7군현과 주민들은 대부분 내륙으로 이주했다. 이후 조선초기에 진도현만이 진도군으로 진도에 복귀했을 뿐, 가흥․임회 2현은 곧바로 혁폐되었고, 나주와 영광으로 교우한 나머지 4군현 역시 선초의 군현제 정비 과정에서 복구되지 못했다.
그리고 옛 진도 3현은 진도군으로 개편되었으나, 나머지 4군현의 영역 중 세종대 후반에 이르면, 현 나주군도 일원과 지도는 나주의 영역으로, 현 임자군도 일원은 영광의 영역으로 편성되어, 19세기 말 지도군의 신설 때까지 지속되었다.Seven Counties called ‘gun’ and ‘hyeon’ were established on Southwestern Islands of Jeolla province in Goryeo period. So-called three Jindo hyeon Counties were on Jindo Island, while Appae-gun County, Jangsan-hyeon, Imchi-hyeon and Yukchang-hyeon Counties were each located on central islands of Naju Archipelago, southern islands of Naju Archipelago, Imja Archipelago, and northern islands of Naju Archipelago. Jido Island was under the jurisdiction of Haeje-hyeon County, and there were not counties established on Heuksando Island. In 1018,three Jindo hyeon Counties, Appae-gun County and Jangsan-hyeon County belonged to the jurisdiction of Naju-mok County, and Yukchang-hyeon County and Imchi-hyeon County belonged to the jurisdiction of Yeonggwang-gun County. In 1143, Jindo-hyeon County was elevated to higher status county directly ruled by the governor, and controlled Gaheung-hyeon County and Imhoe-hyeon County of Jindo Island under its jurisdiction. The jurisdiction over Appae-gun County was moved from Naju to Yeonggwang-gun County. The Seven County centers and their residents moved to mainland of Jeolla province in order to escape from Japanese marauders in the end of Goryeo period. After the foundation of Joseon dynasty,Only Jindo-hyeon County could return to original place as Jindo-gun County.
Gaheung-hyeon and Imhoe-hyeon Counties were abolished, and the other four Counties, which had moved inland in the end of Goryeo period, were never restored in the course of reforming local administrative system in the early Joseon period.
In the later period of King Sejong’s reign, the former four Counties’ areas were reorganized, thus current Naju Archipelago and Jido Island were incorporated into Naju jurisdiction and current Imja Archipelago were also reorganized as a part of Yeonggwang area. This local administrative formation lasted until the establishment of Jido-gun County in the end of the nineteenth century.