The above picture should give a clear picture of how I would wager the Etrusco-Rhaetic languages entered Italy by the beginning of the 1st millennium BCE. I can't help but conclude one thing: the Etruscan and Rhaetic languages eminated from the eastern coast of the Po Valley and spread out from there.
Larissa Bonfante rejected this immigration from the north[1], attributing the presence of Rhaetic instead to later Etruscan colonization into the Po Valley in the 6th century based on Livy. Her vague and confusing conclusion is that "the sequence of the prehistoric and protohistoric cultures of Italy appears to be continuous from the Bronze Age throughout the early part of the Iron Age, without any interruptions which might have been caused by invasions or the arrival of a new people." Yet the presence of Mycenaean trade in the Po Valley as early as the 12th century BCE, which was known before she even published her 1986 book[2], strongly makes me want to reject Bonfante's input and go with my instinct. Any Central European influence on the Po Valley, seemingly by land, would naturally be facilitated all the more by Adriatic sea trade so this fact is unsurprising and doesn't say much in itself about cultural continuity of the Villanovan culture separate from its possible cultural exchange with C.Europe. So I'm admittedly confused on this.
From a linguistic perspective, something that I don't feel Bonfante is going by, it makes the most sense that the Po Valley would serve as a linguistic epicenter from which the Rhaetic idiom would spread north while the Etruscan dialect would swoop to the south and west. Note however that I'm speaking strictly about linguistic movements, not cultural, economic or demic movements.
Taking this for granted, it interests me that the first languages to greet Etrusco-Rhaetic would have to be Venetic, North Picene, and Umbrian. I've been working on word etymologies in Etruscan and I'm finding that some origins of certain words are hard to determine. For example, we could take Etruscan ais 'god' to be a very early Italic loanword, perhaps from Umbrian, yet there is also Venetic aisu- 'god' to ponder on. Which one is the correct source? The word lautuni 'freeman' is so obviously un-Etruscan (< PIE *h₁leudʰ-) yet which language did it come from more precisely? Is it Venetic again? The verb fac , also foreign because of f- without neighbouring u to trigger lenition as it does in so many other circumstances, might be Umbrian fak- or it might be from Venetic, as in its sigmatic form fagsto 'he did/made'. And in what way has the mysterious North Picene language, as exemplified by the Novilara Stele, influenced Etruscan and Rhaetic? While I'd dare estimate that North Picene is Indo-European, it has a unique flair that's hard to classify and few words to come by. Then there's Illyrian... more mystery. All of these poorly attested languages huddle the Adriatic, as we can see in the above map, and it piques my interest all the more while hampering my quest for solid Etruscan etymologies and historic linguistic interactions.
NOTES
[1] Bonfante, Etruscan life and afterlife: A handbook of Etruscan studies (1986), p.48 (see link).
[2] Smith, Early Rome and Latium: Economy and society c. 1000 to 500 BC (1996), p.25 (see link); Castleden, Mycenaeans (2005). p.194 (see link); Cadogan, Palaces of Minoan Crete (1991), p.39 (see link); Evans/Evans, The Palace of Minos: A comparative account of the successive stages of the early Cretan civilization as illustrated by the discoveries at Knossos, vol 2, pt 1 (1964) , p.176 (see link); Collis, The European Iron Age (1997), p.34 (see link).
