The book is comprised of three parts: 1) Discovery of the origin of rice agriculture and Yangtze River civilization in southern China was mainly based on the investigation of the Chentoushan archaeological site which is the earliest urban settlement in East Asia. The origin of rice cultivation can be traced back to 10000 BCE and the urban settlement starts at 6000 BP; 2) Collapse of the Yangtze River civilization at 4200 BP. Palaeoenvironmental studies including the analyses of annually laminated sediments in East and Southeast Asia indicate the close relationship between climate change and the rise and fall of the rice cultivating and fishing civilization ; and 3) Migration of the people from southern China to Southeast Asia after 4200 BP. Archaeological investigation of the Phum Snay site in Cambodia, including the analyses of DNA and human skeletal remains, reveal the close relationship with that of southern China indicating the migration of the people from southern China to Southeast Asia. This publication is an important contribution for understanding the environmental history of China and Cambodia in relation to the rise and fall of rice cultivating and fishing civilization which we call water civilization.