The Map displays the selected polity during the chosen year, with its regions colored according to population density.

In the calculation, we used polygons based on subdivisions within modern-day countries. For specific polities or clusters, we only considered the regions where these subdivisions intersect with the polity or cluster. This method can make polygons near large modern cities appear smaller, potentially inflating their population density. Population figures for polities are always calculated as of January 1st of the relevant year.

Polities are the smallest unit in the Phersu Atlas model. They represent political entities that control a territory, regardless of their form. Polities can be either independent or dependent.