It is said that a profound change can be noticed in the accents and speech patterns of Italians who live north of a line that runs from La Spezia to Rimini, roughly the area of ancient Cisalpine Gaul. The area was once Celtic speaking. Did Gaulish (Celtic) really have a deep influence, or a minor one in the accents of N. Italy? It has been mentioned by Roman historian Strabo, that most of the Celts who were conquered there either fled, were enslaved, or put to the sword. Was there a substantial Celtic presence in N. Italy after it was conquered and colonized by the Romans?
Celtic influences in Northern Italian Dialects
It is said that the people of Cisalpine Gaul spoke Latin with a Celtic substratum, which I don't doubt. However, I believe the languages of Northern Italy were largely influenced by later powers that came to dominate this region after the fall of Rome: The Lombards, the Franks (Burgundians), the Holy Roman Empire, Savoy, France (southern and later northern), etc.
"It is said that the people of Cisalpine Gaul spoke Latin with a Celtic substratum"
This is correct. Northwestern Italian dialects, especially Piedmontese, underwent the same influences as Occitan, with which they used to form a dialect continuum. The use of front rounded vowels like "ΓΌ" (that were unknown in Latin) and dropped final vowels are clearly a Celtic legacy.
This doesn't apply however to the Venetian language that sounds absolutely different (closer to standard Italian or in some way to Spanish).
This is correct. Northwestern Italian dialects, especially Piedmontese, underwent the same influences as Occitan, with which they used to form a dialect continuum. The use of front rounded vowels like "ΓΌ" (that were unknown in Latin) and dropped final vowels are clearly a Celtic legacy.
This doesn't apply however to the Venetian language that sounds absolutely different (closer to standard Italian or in some way to Spanish).