Attribution
World Empires relies on two open datasets. Their licences require the following attribution.
Seshat Cliopatria
Licence: CC BY 4.0 — Creative Commons Attribution 4.0 International
- Licence
- CC BY 4.0
- Attribution string
- Seshat Cliopatria, Seshat: Global History Databank (seshatdatabank.info), licensed under CC BY 4.0.
- Version / snapshot date
- Cliopatria v2024 snapshot (downloaded 2026)
- Coverage
- Dated polity polygons with NGA GeoNet Names and Wikidata identifiers, spanning approximately 3000 BC to 1945.
Data transformations applied: Feature IDs were normalised to deterministic integer identifiers based on wikidata and name fields. Geometries were simplified using Mapshaper (Visvalingam–Whyatt algorithm, 10% quality) for web delivery. Features were sliced into 45 per-snapshot-year GeoJSON files. Polity–polygon joins use the Wikidata identifier as the primary key, with name-based matching as a fallback where Wikidata IDs were absent or misassigned.
Natural Earth
Licence: Public domain, no restrictions on use
- Source
- naturalearthdata.com
- Licence
- Public domain (terms of use)
- Version
- 1:10m Cultural and Physical Vectors, v5.1.2
- Usage
- Base layer coastlines, lakes, and administrative boundaries used as a reference basemap behind the Seshat polygon overlay.
MapLibre GL JS
Licence: BSD 3-Clause
- Source
- maplibre.org
- Licence
- BSD 3-Clause (view)
- Version
- 5.24.0
- Usage
- Client-side map rendering engine for the interactive atlas view.
Site code and editorial content
The World Empires application code and all original editorial copy (polity summaries, event descriptions, and compiled chronologies) are copyright © 2026 World Empires. All rights reserved. The underlying map data remains subject to its original licences above.