"Celt" Conjecture

[MD]

Was he? Did he? Let's see. For instance, Caesar described significant social, economic and cultural differences between people west (Gauls) and east (Germans) of Rhine. Generally the latter were more primitive, poor and savage than the Gauls. Should we believe that? Well, of course not.

The archaeology of the Late Iron Age argues for a north-south articulation of the northwest European continent, in which the Rhine does not function as a cultural boundary. However, as part of the new politico-geographic order, all emphasis in Roman Germani discourse came to lie on the east-west articulation, with the Rhine functioning as a boundary between the civilised world and a world of barbarism.

Exactly.

Oppida existed only in the southern portion of modern Germany, not further north than central Hesse and southern Thuringia.
In Hesse, which is closest to Caesars Rhine crossing most Oppida and Celtic settlements were abandoned around the end of La Tene D1 (except Duensberg), thus maybe already two decades before Caesars Gallic war maybe they were still inhabited when arrived. In every case these Oppida were already in decline.

Caesars crosses the Rhine in the territory of the Ubii. He considers them a Germanic tribe, but has to admit that they're more civilized and have some Gallic customs (BG IV 3). These people may very well be the same that inhabited the Oppida. Later (BG VI 24) he mentions that Gauls (Volcae Tectosages) are still living east of the Rhine. Thus there isn't any real contradiction between Caesars writings and archeology.