Book excerpt: The centre may hold, but borders can fray. Frontier Fieldwork explores the work of social scientists, agriculturists, photographers, and missionaries who took to the field in China’s southwest at a time when foreign political powers were contesting China’s claims over its frontiers. In the early twentieth century, when the threat of imperialism loomed large in the Sino-Tibetan borderlands, these fieldworkers undertook a nation-building exercise to unite a disparate, multi-ethnic population. Andres Rodriguez exposes the transformative power of the fieldworkers’ efforts, which placed China’s margins at the centre of its nation-making process and race to modernity.