As China and India build modern highways through the Tibet-Nepal borderlands, traditional livelihoods, land use patterns, and trade relations are rapidly changing for numerous highland communities across the Trans-Himalaya interface. In response to recently opened border crossings, various social and market networks have (re)emerged, transforming the parameters of mobility for the populations of High Asia. New roads are critical to these transformations.Merging Science and Technology Studies (STS) and Marxist analytics to unpack the "black-box" of roads, this study asks two main questions: what are the factors at play in this socio-cultural and geopolitical transition in the Trans-Himalaya borderlands, and how can roads be thought of as technological objects central to this dynamic? After situating the study in the conceptual framework of Zomia, I then draw on Actor Network Theory (ANT), co-production, and the spatial fix to analyze two contemporary trans-border road development projects in Sikkim, India and Mustang, Nepal.