Frontier is an asymmetric socio-spatial designation imposed by centralized power over marginal places. It carries overlapping meanings and functions: an ever-expanding space sustaining capitalist expansion, the limit of state power and capitalist reach, and an imagined wild and empty space that invites settlers’ imagination of conquest and reward. An imposition of a frontier category over highlands’ nature and people often entails the (re-)ordering of marginal political-economic conditions, sociocultural lives, environment, and human-nature relationships. Various experimentations are embedded in this (re-)ordering, including economic exploitation, technocracy, territory, science, and technology. The SEAF Workshop Series #1 aims at discussing the initiations, processes, and impacts of frontierization of Southeast Asian highlands’ nature and people.