at the Namsan settlement, located on the top of a hill 100 m above sea level in modern Changwon City, Gyeongsang Nam-do. A shellmidden (shellmound) was found in the vicinity of Namsan, indicating that, in addition to agriculture, shellfish exploitation was part of the Late Mumun subsistence system in some areas. Pit-houses at Namsan were located inside a ring-ditch that is some 4.2 m deep and 10 m in width. Why would such a formidable ring-ditch, so massive in size, have been necessary? One possible answer is intergroup conflict. Archaeologists propose that the Late Mumun was a period of conflict between groups of people. The number of settlements in the Late Mumun is much lower than in the previous sub-period. This indicates that populations were reorganized and settlement was probably more concentrated in a smaller number of larger settlements. There are a number of reasons why this could have occurred. There are some indications that conflict increased or climatic change led to crop failures. Notably, according to the traditional Yayoi chronological sequence, Mumun-esque settlements appeared in Northern Kyūshū (Japan) during the Late Mumun. The Mumun period ends when iron appeared in the archaeological record along with pit-houses that had interior composite hearth-ovens reminiscent of the historic period (agungi). Some scholars suggest that the Mumun pottery period should be extended to 0 BC because of the presence of an undecorated ware that was popular between 400 BC and 0 BC called jeomtodae (). However, bronze became very important in ceremonial and elite life from 300 BC. Additionally, iron tools are increasingly found in Southern Korea after 300 BC. These factors clearly differentiate the time period 300 BC - 0 from the cultural, technological, and social scale that was present in the Mumun pottery period. The unequal presence of bronze and iron in increased amounts from a few high status graves after 300 BC as sets this time apart from the Mumun pottery period. It is thus that, as a cultural-technical period, the Mumun was finished by approximately 300 BC. From about 300 BC, bronze objects became the most valued prestige mortuary goods, but iron objects were traded and then produced in the Korean peninsula at that time. The Late Mumun-Early Iron Age Neuk-do Island Shellmidden Site yielded a small number of iron objects, Lelang and Yayoi pottery, and other evidence showing that beginning in the Late Mumun, local societies were drawn