This study examines the structural remains, Sanskrit inscriptions, and iconographic programs of three monumental temple complexes from Vietnam, Laos, and Java between the fifth and the tenth centuries CE, to show how centuries of accretional building practices produced architectures designed to colonize powerful places and transform indigenous sacred geographies into political landscapes dedicated to Hindu deities. In early Southeast Asia, distinctive mountains, natural springs, and rivers revered as the abode of tutelary deities, ancestors, and the heart of subsistence economies, were systematically redesigned as royal temple sites dedicated to Hindu deities beginning in the fifth century CE. More than eye-catching landmarks, these natural wonders were considered manifestations of divine presence. This religious ecology, in which the physical geography was fully saturated with power and agency, was the basis for the development of a political ecology in which the landscape was similarly understood as a source of empowerment. The temples and built landscapes of this book's three case studies were effective agents of empire because their design enabled the control of natural places that were widely recognized as sources of divine power. This interdisciplinary research creates a framework for a new material history of religion in premodern Southeast Asia that is grounded in the study of primary sources, supported by on-site research, and socially and environmentally engaged.