With the advent of extensive on-line databases of curated historical information about productivity, population, trade, warfare, technology, etc., the scientific understanding of world-wide historical dynamics of states has made significant progress. For example, recent work has identified important causal regularities in the rise, spread, and fall of complex societies utilizing spatially-explicit models and exploring empirical evidence that incorporated geospatial and temporal information. More traditional historical investigations have also engaged geospatial information, often concentrating on highly localized maps of particular cultures, or regional maps to highlight the spread of languages8 or growth in inter-regional exchange9,10. Similar efforts in economic history have utilized geo-spatial boundaries to explore the historical rise and spread of critical productive technologies and institutional packages argued as fundamental in the development of economic growth. In lieu of good historical boundary data, however, these later efforts often use contemporary geo-spatial borders, which can mask important political developments in the past and can lead to measurement errors.

As these examples suggest, a wide range of studies across numerous disciplines depend upon and would benefit from a more comprehensive digital encoding of world-wide historical political geographies in time. Facilitating comparative analysis across social, spatial, and temporal bounds, including developing correspondences between different disparate geographical datasets, requires that the underlying geo-referenced data be represented as points, lines, and polygons in industry-standard digital encodings, such as shape or GeoJSON files.

Various attempts to construct such digital datasets have focused on a particular period or region of the world, digitizing maps at differing resolutions and sampling intervals. However, these datasets are not comprehensive, even taken together17. Other efforts have sought to compile point-based data, which tend to be somewhat broader in scope but represent only one particular type of spatial information. Yet other efforts catalog geo-referenced images of historical maps for visual inspection and summary but that limit automated computation of, for example, relative changes in political areas.

Several efforts, such as GeoCron or Running Reality, have created more comprehensive world-wide digital representations of political entities over time. However, at present, their underlying data are not easily available to scholars. As of this writing they either require a license or they are encoded in a proprietary database scheme with limited options for exporting the data in other formats more amendable to computational analysis. Further, to our knowledge, the references used in their construction are not available.

Here we describe Cliopatria, a comprehensive open-source geospatial digital dataset of worldwide polities — namely political units independent of higher authority which can range from city-states to empires, centralized or not1 — from 3400BCE to 2024CE. We describe the construction and contents of the initial version of the database, describe its validation, discuss how it compares to other digital databases, and note limitations and important considerations in its use. Subsequent versions of Cliopatria, which address these limitations (and any inaccuracies), will follow the established review procedures of the Seshat: Global Historical Databank project.