Focusing on the relationship between royal authority and the natural environment, it interprets this transition as a process through which sallim-sut'aek (山林藪澤)—a landscape of forests, streams, wetlands, and marshlands—was gradually transformed into political space. By analyzing references to Kŭmsŏng, royal residences, and Sirim (始林) in the Samguk sagi and Samguk yusa, this study argues that the early Saro ruling elite maintained a political base closely associated with the western slopes of Namsan. It also suggests that the environmental constraints and defensive limitations of this area encouraged increasing attention toward the forested and wetland landscape of the central basin. A comparative examination of the Talhae tradition concerning the selection of the Wŏlsŏng site and early capital-location narratives in Koguryŏ and Paekche indicates that the central Kyŏngju Basin was perceived as a favorable setting in terms of resource availability, defensive advantages, and symbolic authority. Drawing on archaeological evidence and studies of the basin's hydrological environment, this paper further reinterprets the gradual formation of Wŏlsŏng as a process of environmental control and spatial reorganization undertaken by royal authority. The transition from Kŭmsŏng to Wŏlsŏng was therefore not merely a relocation of a royal center. Rather, it was a process through which royal authority appropriated and reorganized the forested and wetland landscape of the central Kyŏngju Basin into a political center. The experience of environmental management accumulated through this process provided an important foundation for the subsequent formation of the royal capital and urban development of Kyŏngju.