The myth of the Celts

Those who say that the Po Valley was colonized by the Celts say a historical nonsense. The Celts never entered the Venetian territory, or from Bergamo to the east, because Bergamo and Brescia, inhabited by cenomani roosters, they were entirely Venetianized, and united with the Venetians against the Celts it was also necessary to save Rome from the Celtic invasion.

But here is another of the many examples of a non-dominance of the Celts in the Po valley

Very little is known about the ancient inhabitants of Valsesia: only thanks to the particular geological structure of Monte Fenera the only possibility for the reconstruction of the prehistory of the valley from its beginnings.
The cavities that open into the west wall, they have in fact yielded many remains of ancient fauna and traces of Neanderthal man and the human groups that followed one another for millennia.
The oldest populations of certain origins belonged to the Ligurian stock, who merged with the "natives" of the valley, also called Sicciani. Like all other Alpine people, they first led nomadic lives, looking for pastures, devoting himself to hunting and herding, finding in the valley the conditions suitable for their development. Legend has it that the Sicciani, of strong and courageous temperament, thanks also to the geographical position of the Valsesian territory without connecting roads, they fought fiercely against every violent invasion of the Celto-Gallic tribes, that, despite long struggles they tried in vain to usurp their territory.

da http://www.valsesia.it/STORIA/preistoria.htm