Historical European boundary layer

Source: Historical Basemaps by Alexandre Ourednik
Repository: https://github.com/aourednik/historical-basemaps
Interactive examples: https://ourednik.info/historicalmaps/
License: GNU General Public License, version 3
License URL: https://github.com/aourednik/historical-basemaps/blob/master/LICENSE
Retrieved: 2026-08-20

Modified on 2026-08-21: the website filters, clips and projects the source GeoJSON to its Europe map, then
splits the projected result into year-based JSON files for on-demand loading. Feature names,
subject relationships, PARTOF values, and BORDERPRECISION are retained where the
source supplies them. Historical borders—especially ancient and medieval ones—are
reconstructions and should not be interpreted as survey-accurate modern borders.