Hundreds of sites of the post-Hoabinhian Middle Neolithic period have been discovered in Vietnam, dating from 7,000 to 4,000 BP. These sites are scattered throughout a variety of topographic regions in Vietnam: the northern mountainous region, Central Highlands, and the coastal plains. This research examines the coastal plain exploration process of the following communities: the Cai Beo culture (Quang Ninh Province and Hai Phong City), Trang An landscape complex (Ninh Binh Province), the Da But culture (Thanh Hoa and Ninh Binh Provinces), and the Quynh Van culture (Nghe An and Ha Tinh Provinces). In so doing it clarifies human adaptation to changes in the ecological environment in each region, the cultural achievements of inhabitant groups in these localities, and the position of communities in the coastal plains in the formulation and development of Vietnam’s prehistoric marine culture.