The Aargau (Latin Argovia, also Araris pagus, Arguna, Argogia or Argoya) first received its name in 763, deriving it from the river Aare which flows through its heart. The first differentiation between Upper and Lower Aargau (Oberaargau and Unteraargau respectively) came in 861. With the expiration of its ruling houses, the Counts von Kiburg and von Lenzburg, the Aargau, partly in 1173 and fully in 1264, came into the control of the house of Habsburg. In 1415, the Swiss Confederation managed to conquer the Lower Aargau, which thenceforth went partly to Bern in the west and smaller parts to Lucerne and Zurich in the east. The rest was subordinated to the eight other cantons. Fricktal consisted of the bailiwicks of Rheinfelden (at that time consisting of the lands Fricktal (proper), Rheintal und Möhlinbach) and Laufenburg and remained under the Habsburgs until 1801.
