The document summarizes the physical geography and early history of Southeast Asia. It describes how Southeast Asia consists of peninsulas, islands, and waterways that support diverse ecosystems. Early humans migrated to the region over 5,000 years ago from Taiwan and South Asia. By the 1st millennium BCE, societies in Vietnam and Thailand used bronze tools and engaged in agriculture and trade. Indian and Chinese cultural influences began arriving in Southeast Asia between the 3rd century BCE and 2nd century CE, bringing Hinduism, Buddhism, and administrative practices that were adopted by local rulers.