A Theoretical Review of Port City Theory and Port Markets in Gaya

This study focuses on the observation that, in recent research on Gaya history and maritime exchange during the Three Kingdoms period, the concept of port market (港市) has been widely applied in advance of a clear theoretical definition. Previous studies have tended to define port markets primarily on the basis of locational conditions or the presence of a limited range of foreign-origin artifacts, while lacking systematic discussion on the developmental stages—from anchorage to trading place, port market, and port-polity—as well as on the internal structure of port markets themselves. In response, this paper reviews the accumulated discussions of Port-Polity Theory (港市國家論) derived from case studies in Southeast Asia, the Indian Ocean, and the Japanese archipelago, and reorganizes the concept, structure, and operational mechanisms of the port market. The core elements are summarized as follows: (1) a nodal location linking maritime routes, waterways, and inland regions; (2) the concentration of foreign-origin materials and multidirectional cultural interactions; (3) a political authority that organizes and controls exchange; and (4) a port network structure integrating trading places, port markets, and their hinterlands. Based on this theoretical framework, a comparative analysis of the Paleo-Gimhae Bay, Geoje Island, and Sacheon within the Gaya region demonstrates clear differentiation. The Paleo-Gimhae Bay exhibits a systematic integration of central place, outer port, and hinterland, alongside a dense accumulation of foreign elements, closely corresponding to the structure of a port polity. In contrast, the Ajou-dong site on Geoje Island shows diverse foreign influences but lacks political centrality, and is therefore best understood as a trading place. The Sacheon area reveals evidence of limited exchange activities, yet the scarcity of foreign elements makes it insufficient, at present, to be interpreted as a port market. By reexamining the concept of Port-Polity Theory and presenting an analytical framework that integrates theory with material culture, this study aims to provide a firmer conceptual foundation for future research on maritime exchange through the lens of port-polity studies.