The Search for the Tang Royal Domain (Wangji 王畿)

This essay discusses how the traditional Chinese geographical concept Nine Domains (Jiufu 九服) was applied in Yixing’s 一行 (683–727) large-scale gnomonic survey of the Tang dynasty. Yixing’s surveying method is reconstructed by comparing textual records with schematic delineations. This comparison shows that the centralized and symmetrical pattern in the arrangement of survey sites conforms to the visual and schematic delineations of the concept of Nine Domains. The design was meant to show that the Earth was in harmony with heavenly patterns, thus confirming Emperor Xuanzong of Tang’s 唐玄宗 mandate of heaven to govern. In this essay, I lay out Yixing’s empirical scientific work and symbolic cultural activity regarding calendrical reform to re-establish the legitimacy of the Tang dynasty regime. The case demonstrates an understanding of how Chinese astronomers interrelated Heaven and Earth and indicates an ongoing tension in the history of science about concept-practice relations.