In the late 1st century CE, Roman troops began extensively securing the area between the Rhine and Danube. The Upper Germanic-Rhaetian Limes marked the border region between the Roman provinces and the settlement areas of Germanic tribes in the north.

In the 3rd century CE, the old Limes was abandoned due to an increase in Germanic invasions, especially by the Alamanni. At the end of the 3rd century, Rome reorganised the provinces. A new system of fortifications was built along the Danube, Iller, and Rhine rivers, and the border region was secured with permanent forts.