During the Gallic Wars of the 1st century BC, the Roman general Julius Caesar came into contact with peoples originating east of the Rhine. In his "Commentarii de Bello Gallico", Caesar refers to these peoples as the Germani, and the lands from where they originated as Germania. The Romans appear to have borrowed the name from the Gauls. Having defeated the Germanic chieftain Ariovistus in Gaul, Caesar built bridges across the Rhine and conducted punitive expeditions in Germania. He writes the area was composed of numerous Germanic states, which were not entirely united. According to Caesar, the Gallic Volcae Tectosages had once crossed the Rhine and colonized parts of Germania, but had since been become militarily inferior to the Germani. He also writes that Germani had once crossed the Rhine into northeast Gaul and driven away its Gallic inhabitants, and that the Belgae claimed to be largely descended from these Germanic invaders.