I seriously doubt that the Germanic tribes were any more or less "barbaric" than any other nomadic people of the time. Tacitus is roundly scorned in historiographic circles these days. He has been shown to be a fraud, a chronic distorter of facts and a propagandist. While he never claimed to have been to Germania, he makes strange statements which suggest he had no real knowledge of his subject at all, such as saying that the Germans all had red hair. The case has been made that his lionising of them was all about goading his fellow Romans, rather than reflecting any real admiration for the Germans. Inspiring fiction perhaps, but of little historical value.