Cisalpine Gaul (from the Roman side of the Alps) was a region that was settled by Celtic peoples from Northern Alpine and Upper Danubian regions in the Vth and IVth centuries (the Gallic origin of these migrations isn't really well supported), but probably being partly Celticized in the First Iron Age and possibly before : the Golasecca Culture is associated with Insubres, a people that was reputed having settled Lombardy before the aforementioned wave of migration. Their language, written in an old Italic script, was definitely Celtic (although it's unsure if it was an archaic dialect of Gaulish, or a distinct language thus called Lepontic); and it's quite possible that Ligurians were at least partly Celtic-speaking too.

We don't really know if and how the Celtic peoples of this regions named themselves or if they even considered themselves as part of a same broad ensemble (Jean-Louis Brunaux seems to think that the lack of regional institutions facilitated the Roman conquests) : military support from Transalpine (as in Gauls from the other side of the Alps) Gauls was more taking the for of a mercenariate (transalpine reinforcements called Gesatae) than trough a system of alliances as it happened during the conquest of Transalpine Gaul. While Romans tended to consider Cisalpine and Transalpine Gauls as essentially akin, this was possibly not the case for their peoples, especially non-Celtic peoples in the region (such as Veneti) whom cultural features were often borrowed by neighboring relations or intermarriage.

Romans considered and named Cisalpine Gauls and Transalpine Gauls alike, but it was more of a Roman perspective than anything else, Galli being a name they first attributed to Celts of northern Italy and then to Celts of Gaul.

While Romans settlers, especially veterans that were settled in these region to form colonies and military recruitment pools (that Caesar liberally used as proconsul), were an important factor in the making of a Roman Cisalpine; its "Romanisation" (a complex dynamic of creolzation and acculturation rather than a sudden shift of culture or identity) comparable to what later happened in Transalpine Gaul, wasn't conceived to make Romans out of Gauls. This was a by-product of the new institutional and administrative network centered on Rome and its institutions (and, thus, its cultural and social expressions) applied to the various peoples of northern Italy : these peoples' elites (that, again, didn't seem to have seen themselves as really unified if at all) encountered then a massive hegemonic political and economical institution they either joined and prospered, or refused and disappeared.