This book takes the origin, introduction, and development of religions in Southeast Asia as the research object, takes "dissemination" and "evolution" as the analysis dimensions, explores the influence of historical evolution and social changes in Southeast Asia on the development of religions, and analyzes the spread of foreign religions and their relationship with local beliefs. Combining the path of evolution, sort out the flow and interaction among religions in Southeast Asia, and summarize the development laws and characteristics of religious history in Southeast Asia. The time period is from ancient times to the middle of the 20th century