The Qasr e Shirin region, located along the historic Khorasan trade route in western Iran, represents a significant cultural landscape that supported both sedentary agricultural communities and mobile pastoral groups during the Sasanian period. This study investigates the spatial organization, settlement patterns, and functional relationships of Sasanian-period sites within the Qasr e Shirin plain using a landscape archaeological approach that integrates Geographic Information Systems (GIS), remote sensing data, and archaeological survey evidence. Spatial analyses were conducted to examine the relationships between archaeological sites and environmental variables, including topography, land use, communication routes, water resources, and vegetation cover. The results indicate that the region was characterized by a dual settlement system consisting of a centralized administrative–agricultural complex and a network of dispersed pastoral settlements. Several sites display characteristics commonly associated with mobile pastoral lifeways, including ephemeral architectural remains, dry-stone constructions, extensive pottery scatters, and locations closely associated with seasonal grazing lands. GIS-based analyses further demonstrate that many of these settlements were located in elevated areas suitable for pastoral activities, whereas major administrative and agricultural centers were concentrated in the lower and more fertile sections of the plain. The distribution of sites, their proximity to communication routes, and their relationship to water resources suggest the presence of an integrated settlement network in which nomadic and sedentary communities interacted within a shared socio-economic landscape. This study argues that pastoral nomadic groups constituted an important component of the Sasanian cultural landscape of Qasr e Shirin and that their settlements formed part of a broader regional system closely connected to agricultural production, administrative authority, and long-distance communication networks. These findings contribute to a more comprehensive understanding of the diversity of settlement organization and human–environment interactions in the western Zagros during the Sasanian period.