Which groups lived in Bavaria before the Romans arrived?

The earliest known inhabitants of the area that is now Bavaria were the Celts.1

Archaeological evidence indicates that these Celtic peoples, associated with the Hallstatt culture and later the La Tène culture, occupied southern Germany and controlled vital trade routes along major river systems, including the Danube. By the time of the Roman expansion into the region around the beginning of the Common Era, these Celtic populations were gradually joined and influenced by Germanic tribes migrating from the north.231