Several studies have suggested that the expansion of Jeulmun settlement sites in the Central West region of Korea between ca. 3500 and 3000 BCE was accompanied by changes in mobility and/or sedentism. However, archaeological interpretations regarding the mobility or sedentariness of Jeulmun groups have often been contradictory. It is argued that these contrasting interpretations largely arise from the misconceptualization of mobility and sedentism as mutually exclusive, dichotomous phenomena. In the context of mobile societies, reconstructing and comparing regional patterns of mobility must take into account potential differences in the occupational length and frequency of sites. I introduce two temporal scales of occupation -‘total occupation length’ and ‘annual occupation length’- that can be applied to archaeologically distinguish between inter-annual and intraannual scales of mobility. As an example of the application of these concepts, I attempt to reconstruct mobility patterns preceding and following the Jeulmun expansion. Measures of investment in dwelling architecture and the frequency of remodeling and reoccupation of dwellings were used to compare the relative total occupation length and annual occupation length of dwellings in the Central-west region before and after the Jeulmun expansion. Preceding the expansion, settlements were used exclusively as large-scale coastal residential bases and were occupied more-or-less continuously over relatively long periods of time. Following the Jeulmun expansion, large-scale coastal villages continued to be used, but were likely occupied for only part of the year and revisited repetitively over a long period of time. Meanwhile, the majority of small-scale sites were likely used logistical or seasonal residences that were occupied seasonally or temporarily, but in some cases, occupied redundantly over multiple episodes. It is inferred that following the Jeulmun expansion, hunter-gatherer-horticultural groups began moving frequently among intermittently occupied large-scale coastal villages and sites of various functions located inland and along the coasts of the Central West region. I suggest that the frequent movement of Jeulmun hunter-gatherer-horticultural groups between large-scale villages and small-scale villages and camps closely resembles the ethnographically observed “fission-fusion social system,” a form of organization in which groups intermittently aggregate into large groups and disperse into small groups at different times of the year. This socio-economic organization would have supported a subsistence economy that depended heavily on wild resources, and at the same time, played an important role in the social and ritual lives of Jeulmun peoples.