This study aims to investigate population dynamics in the Mahan, Baekje, and Ye regions. Settlement sites excavated in the Seoul-Gyeonggi, Yeongseo, Hoseo, and Honam regions, along with associated radiocarbon dates (2000-1300 BP), were compiled to assess their temporal and spatial distribution. Following adjustments to ensure the representativeness of the radiocarbon dates, trends in population growth and decline over time were analyzed using summed probability distributions of radiocarbon dates. Overall, a gradual increase in the density of radiocarbon dates was observed, peaking around 1750-1550 calBP before declining. This decline was attributed, to some extent, to changes in residential patterns and significant sampling biases. Regional analyses revealed variations in the timing and magnitude of population changes, with an earlier decline observed in the Yeongseo region around 1700 calBP compared to other regions, while the Hoseo and Honam regions experienced significant increases from around 1750 calBP before declining after 1550 calBP. Spatial distributions examined through kernel density analysis corresponded to these findings. While interpreting these changes based solely on the analysis presented herein may be insufficient, considering previous discussions, it is suggested that changes in trade networks and military tensions may have been important factors contributing to the early population decline in the Yeongseo region and northern Gyeonggi Province. Additionally, further investigation is required to provide a more convincing explanation for the significant population increase in the Mahan region during the period of Baekje's expansion.