Expressing history through a geo-spatial ontology

Conventional GIS systems struggle to represent uncertain and contested historical knowledge. An ontology, meaning a semantic structure defining named entities, and explicit and typed relationships, can be constructed in the absence of locational data, and spatial objects can be attached to this structure if and when they become available. We describe the overall architecture of the Great Britain Historical GIS, and the Administrative Unit Ontology which forms its core. We then show how particular historical geographies can be represented within this architecture through two case studies, both emphasizing entity definition and especially the application of a multi-level typology, in which each “unit” has an unchanging “Type” but also a time-variant “Status”: firstly, the linked systems of Poor Law Unions and Registration Districts in nineteenth century England and Wales, in which most but not all Unions and Districts were coterminous; secondly, the international system of nation-states, in which most units do not appear from nothing, but rather gain or lose independence. We show that a relatively simple database architecture is able to represent much historical complexity.