My dissertation analyzes the crafting of notions on territory, ethnicity, and nation in the Amazonian region now shared by Ecuador and Peru, and historically known as Maynas. My objective is to demonstrate (1) that between the late seventeenth and early nineteenth centuries Jesuit and Franciscan cartographies played an important role in the systematization, and eventual nationalization, of the knowledge about territories and societies in Western Amazonia, and (2) that this process of knowledge making on Maynas depended upon relationships missionaries established with Amazonian natives. The research I propose studies how ideas of territoriality and ethnicity were the result of interactions between missionaries and Amazonian natives, and how missionary scientific networks influenced the ways in which Maynas and its inhabitants became Ecuadorian or Peruvian after independence. My general goal is to generate new theoretical and practical appreciations in regard to the crafting of spatial and national identities.