The burgeoning literature on the legacies of historical institutions depends to a large degree on data measuring experiences of historical statehood. While data on historical states in Europe and the Americas has existed for some time, we still lack comparative data on historical states in Africa, Asia, and the Middle-East. We outline two fundamental challenges to collecting data on historical states that arise from variations in how sovereignty was exercised and imagined, what we call ontological and epistemological uncertainty. We then outline a new method for identifying and mapping states from 1750-1920 century that incorporates these uncertainties and creates flexible estimates of state boundaries and presence that better captures the topographical nature of sovereignty in the precolonial world. These estimates are used to explore the extent to which "old" boundary regions are associated with armed conflict events since the end of the Cold War.
