In the late 1st and early 2nd century AD, the Romans reoccupied areas lying between the Rhine, Main and Danube rivers. This area became known as the Agri Decumates. Additional numbers of Germani were settled by the Romans within this area. The Roman fortifications on the border with Magna Germania were known as the Limes Germanicus. The 3rd century AD saw the emergence of several powerful Germanic confederations in Magna Germania, such as the Alemanni and Franks. The Crisis of the Third Century included raids on Roman Germania by Alemanni and Franks, and the area briefly became part of the Gallic Empire established by the usurper Postumus. Around 280 AD, the Agri Decumates were evacuated by the Romans and occupied by Alemanni.