Map data licences for the files in this folder
==============================================

eras/*.json (2000 BCE to 2010), polities.json, rulers-grid.json, era-stats.json
  Derived from historical-basemaps by André Ourednik and contributors
  https://github.com/aourednik/historical-basemaps
  Licence: GNU General Public License v3.0 (GPL-3.0)
  https://www.gnu.org/licenses/gpl-3.0.html

  Changes made for this site: simplified and quantized outlines, renamed or
  re-assigned rulers where the source was wrong for its year, filled unmapped
  land, and split a few shapes. Every change is listed at /about and in
  src/content/data-corrections.json; the build script is scripts/build-data.mjs.
  These derived files are distributed under the same GPL-3.0 licence.

eras/present.json and us-states.json
  Natural Earth (public domain), https://www.naturalearthdata.com/
  US states: US Census Bureau via us-atlas (public domain)

Population figures: World Bank (CC BY 4.0), https://data.worldbank.org/