Shell middens are archaeological sites where ancient coastal inhabitants discarded shells, fish bones, and everyday tools. These middens provide insights into the ecological and environmental conditions of the time, as well as human life. Saemangeum is a region on the Korean peninsula where shell middens are found in concentration.

Before the development of roads and railways, rivers and seas were the main transportation routes for goods. Many ships traveling north from the southern coast passed through the Saemangeum area, where a sunken ship laden with celadon was recently discovered. A Goryeo-era ship found off the coast near Sipyidongpa Island in Gunsan is believed to have been carrying celadon produced in Gangjin, Jeollanam-do, and sank on its way to Gaegyeong. Celadon has also been found in the sea near Bieungdo Island in Gunsan.

During the Joseon period, coastal fortifications and signal fire stations were constructed at strategic maritime locations to defend against Japanese pirate raids. Naval bases were established where warships and troops were stationed. The Saemangeum area, a vital maritime route, also saw the installation of multiple naval bases due to the persistent threat of pirate attacks. Among these, the Wido Naval Base and the Gogunsan Naval Base managed the naval defenses along the northern coast of Honam. Following the Battle of Myeongnyang, Admiral Yi Sun-sin, noted for his leadership from 1545 to 1598, reported his victory from the Gogunsan Naval Base and reorganized his naval forces, solidifying it as a key defensive location along Korea's western coast during the late Joseon era.

Gimje in North Jeolla Province became the largest rice production area due to the intensive development targeted by Japan after the opening of Gunsan Port. Gunsan was cultivated as a colonial hub city to export rice produced in the Gimje-Mangyeong Plains to Japan and sell Japanese products in North and South Chungcheong Provinces.

The first groundbreaking for the Saemangeum Reclamation Project took place on November 28, 1991, and the final closure construction was completed on April 21, 2006. The dike was completed on April 27, 2010, nearly 19 years after commencement. The development within the dike is ongoing with a target completion year of 2050. Initially planned as an agriculture-centered development, it is now being developed into a space harmonizing new industries, new cities, eco-friendly agriculture, tourism industry, and international economic zones.