Every state, kingdom, empire or republic this atlas records as a political entity: from ancient conquest empires through medieval kingdoms to the sovereign states governing today, grouped by form of polity, empire, kingdom, caliphate, Chinese dynasty, historical republic, or a present-day state's monarchy-versus-republic split, rather than by the era each existed in, because a polity typically persists across many eras. This category excludes the events a polity took part in and the organizations chartered under it, each its own category, and it excludes a polity's enduring territory and borders, which is Geography's own historical-geography facet.