"All Factions Horde"

[Luciano B]

and maybe for native sicilians?

No indeed. The Sicels established in Sicily long before the Greeks or the Phoenicians had arrived there. They were a nation with a definite link with the regions occupied by them in historical times.

The Gauls are another story, since except the Insubres who emerged from a local Celtic culture, all the other Gaulish factions (Boii, Cenomani, Senones) had passed in Italy during the great invasions of the late V/early IV century BC, so few dozens of years before the start date of the timeframe covered by our mod.

Also the Taurini had another different story; they were a "Celto-Ligurian" group, resulting after the intermixing of Celtic newcomers with the ealry Ligurian hinabitants of those regions: the Ligurian element was however predominant, so I'd leave them without the "hording" capability.

[Photo Finish]

Could this not also be the case for oscan tribes? They were decentralized mountain tribes keen on raiding lower settlements. Perhaps a small horde comprised of low quality units could represent insurgents for some of the factions more famous for their patriotism and fighting for their sovereignty? Again, the oscans and galls come to mind first.
EDIT since captured cities do not usually get to rebel afterwards when human player is involved, the second suggestion could add to the liveliness of other factions.