During the early modern period, the Holy Roman Empire was divided into imperial circles (Latin: Circuli imperii; German: Reichskreise [ˈʁaɪçsˌkʁaɪzə]; singular: Circulus imperii, Reichskreis [ˈʁaɪçsˌkʁaɪs]), administrative groupings whose primary purposes were the organization of common defensive structure and the collection of imperial taxes.
The Crown of Bohemia, the Swiss Confederacy and Italy remained unencircled, as did various minor territories which held imperial immediacy.
The Upper Saxon Circle was dominated by the electorates of Saxony (plus its satellite Ernestine duchies) and Brandenburg.
In 1747, Friedrich Carl Moser noted that "the preservation of the imperial system depends largely upon .
"[1] Some historians go even farther, like Hanns Hubert Hofmann, who suggests that "all real state-like functions of the Reich lay exclusively with the circles, not the diet.
It created a fixed constitution for the circles and gave them authority to keep civil and religious peace in their teritories.
The Austrian and Burgundian circles, both dominated by possessions of the Habsburgs, never developed full constitutions in the first place.