from their heartland, the franks gradually conquered most of roman gaul north of the loire valley and east of visigothic aquitaine. at first they helped defend the border as allies; for example, when a major invasion of mostly east germanic tribes crossed the rhine in 406, the franks fought against these invaders. in the region of paris, roman control persisted until 486, a decade after the fall of the emperors of ravenna, in part due to alliances with the franks.