The Formation of Late Gaya and the Theory of Upstream State Formation along the Nakdong River

This paper discusses the process by which the polities of Late Gaya emerged following the dissolution of Early Gaya. The Late Gaya polities—such as Ara, Bihwa, Dara, Gara, Seongsan, and SoGaya—did not emerge simultaneously but were established sequentially as they moved upstream along the Nakdong River.I propose naming this phenomenon the “Nakdong River Upstream Theory.” Although this study takes a general approach, its main arguments are based on a comprehensive synthesis of my previous research on tomb, horse harness, armour, pottery, chronology, and related topics. The key to this line of reasoning lies in identifying the founding periods of each small polity by determining the earliest royal tombs. Representative examples include Tomb No. 45 at Malyisan in Haman for Ara, Tomb No. 23 at Okjeon in Hapcheon for Dara, and Tomb No. 73 at Jisan-dong in Goryeong for Gara. For Bihwa, Seongsan, and SoGaya, materials that can either be considered their earliest royal tombs or are otherwise comparable have been selected. From Ara to Dara, these small polities emerged before the appearance of the high-mounded tomb tradition. By contrast, Gara and Seongsan were established as Late Gaya small polities with the advent of high-mounded tombs. Another important implication of the formation of Late Gaya is that this period marks the beginning of full-scale development in the western Gyeongnam region, centered on the Nakdong River. Consequently, at the time these polities emerged, population concentration became possible along two major routes: the Geumho River corridor—including Gyeongju, Gyeongsan, and Daegu— and the Nakdong River corridor, encompassing Busan, Gimhae, Haman, Changnyeong, Hapcheon, and Goryeong, where the Late Gaya polities were located.