This study revisits one of the most extensive examples of the spread of ideas in the history of civilization: the diffusion of Indian religious and political ideas to Southeast Asia before the advent of Islam and European colonialism. Hindu and Buddhist concepts and symbols of kingship and statecraft helped to legitimize Southeast Asian rulers, and transform the political institutions and authority of Southeast Asia. But the process of this diffusion was not accompanied by imperialism, political hegemony, or colonization as conventionally understood.