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, perché Bergamo e 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: solo grazie alla particolare struttura geologica del Monte Fenera l’unica possibilità per la ricostruzione della preistoria della valle dai suoi albori.
Le cavità che si aprono nella parete ovest, hanno infatti reso moltissimi resti di un’antica fauna e le tracce dell’uomo di Neanderthal e dei gruppi umani che si sono succeduti per millenni.
Le popolazioni più antiche di origine certe appartennero al ceppo dei liguri, che si fusero con gli “indigeni” della valle, 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, lottarono accanitamente contro ogni violenta invasione delle tribù celto-galliche, that, despite long struggles they tried in vain to usurp their territory.
da http://www.valsesia.it/STORIA/preistoria.htm