A dynamic and interactionist multiplex order existed in the classical eastern Indian Ocean corresponding with modern Southeast Asia (~1^st—15^th centuries CE). This regional order was not the product of superior Chinese imperial/material power, or some essentialist version of the tributary system. Nor did Indic ideas spread “naturally” into an ideational vacuum in Southeast Asia. This order was in fact an outcome of Southeast Asia’s active agency in fostering connectivity with Chinese and Indian polities, and the consequent material and ideational interactions that ensued. The multiplex order in the eastern Indian Ocean was a highly robust and resilient order that lasted for centuries even in the absence of a grand design. It did not depend exclusively on any single polity, not even imperial China.