About & credits
How it works
Every puzzle is a globe drawn as it would have been printed on a secret date. Spin it, zoom in, and name the year in six guesses. The answer is a window of time, not a single year: the stretch during which that exact set of borders and names existed. Any year inside the window wins.
Where the borders come from
- OpenHistoricalMap — dated country boundaries. Only elements released under CC0 are used.
- Wikidata — names, dates and which country governed each dependency (CC0).
- Natural Earth — coastlines, lakes, Antarctica and present-day outlines (public domain).
- Wikipedia — read for research on disputed and undefined borders. No text is copied; the pages used are linked in the project's data files.
- Yearth's own edits — where the historical data has gaps, we fill them by hand (for example the four occupation zones of Germany, 1945–49, and the Italian-administered Trust Territory of Somaliland). These are released as CC0.
Dashed lines
A dashed border marks one that was undefined, provisional or disputed at the time. Where a border was never drawn at all, such as parts of the Arabian interior, its position on the globe is approximate.
Spot a mistake?
Historical data is messy and we will get things wrong. After a game, use Is this globe wrong?, or the Feedback button at any time.