This investigation covered the original settlement of Lao Song in Sip Song Chu Tai region in northern Vietnam, their first settlement in Phetchaburi Province in central Thailand after their migration, and their migration to other provinces in the Central Plains. It also included the ecological changes that obliged the ethnic group to create multi-level social mechanisms in order to maintain their ethnicity. More importantly, their animistic belief in ancestor spirits is regarded as their cultural root in the whole system. The belief is so strong that it has created various social networks.