This work not only seeks to explain the function and timing of the Cambodian earthwork sites but utilizes the circular earthworks as a case study in understanding the nature of adaptation and temporal affiliation of Neolithic open-air settlements across Mainland Southeast Asia. A further aim of the study is to understand the circular sites of Cambodia in the broader regional context of Southeast Asian prehistory. The earthwork sites, which also extend into what is now the Socialist Republic of Vietnam, appear to represent a distinctive subset within a larger domain of sites having a circular morphology. The age, nature, and articulation of the Cambodian earthworks are examined to advance initial interpretations as to the degree of site community and the extent of group cohesion.