This article proposes the concept of the maritime geo-body as a new framework for reconsidering the history of Central Vietnam in the pre-modern era beyond the perspectives of traditional historiography. Rather than viewing Central Vietnam as a southern “frontier region” gradually incorporated into the territory of Đại Việt through the Vietnamese southward expansion (Nam tiến), the article argues that Central Vietnam was fundamentally a sea-oriented space shaped primarily by maritime routes, port cities, river mouths, and interregional trade networks. Building upon Thongchai Winichakul’s concept of the geo-body, the article extends the analytical focus from terrestrial territory to maritime space, viewing the sea not as a boundary but as a medium of economic, cultural, and political connectivity. Within this framework, Champa represented the formative stage of the maritime geo-body of Central Vietnam, characterized as a maritime polity based on marine exploitation, maritime trade, and exchange networks linking the coastal zone with the highlands. Subsequently, the Vietnamization of Central Vietnam under the Nguyễn Lords involved the appropriation, restructuring, and institutionalization of this preexisting maritime geo-body, leading to the emergence of a distinct socio-economic and political space that combined maritime characteristics with close connections to the continental hinterland. By applying the theory of the maritime geo-body, the article reconsiders conventional land-based interpretations of Central Vietnamese history, clarifies the distinctive identity of the region, and contributes to rethinking the formation of the Vietnamese state in the pre-modern period.