It comprises the area between the Lindenberg and Heitersberg and from the terminal moraine at Othmarsingen to Reuss river in Dietwil.

A Freiamt in the Middle Ages is not a specified area, but a union of persons or free peasants who had a local court or limited self-government.

The term comes from the Alemannic legal breakdown between free and unfree, which in the Early Middle Ages included the rights of autonomy.

The Aargau Freie Ämter were territories that were under Habsburg rule but were independent with respect to low justice and common law, and so under the medieval definition, they were "free".

[1] In the Frankish-Carolingian era the territories to the left of the Reuss belonged to Aargau, while those to the right were part of Thurgau.

[1] On 16 November 1414, Emperor Sigismund called the Council of Constance to settle the Western Schism between the three popes (Benedict XIII, Gregory XII, and John XXIII), all of whom claimed legitimacy.

Under Habsburg rule Aargau was divided into multiple sections (German: Ämter), which were maintained under the Confederation.

The final boundary was set in 1425 by an arbitration tribunal and Lucerne had to give the three Ämter to be collectively ruled.

After the defeat of Zurich in the second Battle of Kappel in 1531, the victorious five Catholic cantons marched their troops into the Freie Ämter and reconverted them to Catholicism.

The victory gave Zurich the opportunity to force the Catholic cantons out of the government in the county of Baden and the adjacent area of the Freie Ämter.

The Freie Ämter were then divided in two by a line drawn from the gallows in Fahrwangen to the Oberlunkhofen church steeple.