@LSCatilina I never talked about tribes being inferior or anything.
Didn't said you were necessarily or consciously : but you use as a stage of social sophistication, rather than a social grouping. it's arguably both, that both survives into later social developments and actually can thrive within.
What I mean in context is that in a Purely tribal economy,outside influences and exposure would be limited and people are more or less very homogeneous.
Tribal economy doesn't hold much water to it, tough : there's no more typical tribal economy than you have chiefdom economy, or typical national economy. It doesn't help that tribes are particularily unstable ensemble because they're defined toward their beighbour and in constant re-arrengement. For instance, groups A, B and C form a tribe B' due to their dominance, and eventually due to shifts, different alliance, inner conflicts, etc, B' tribe end ups being formed of A,B and D while C is included into another tribal ensemble or goes its own way. It's actually because you have these humans groups reciecing outside influence that they feel the necessity to resort to greater-scale identification in spite of regular reshuffle.
The idea that tribes, by essence, are in an ethnographic statis bubble without outside influence suddenly confronted to cosmopolitan cities isn't supported by evidence. First urbanisation is tribal, and tends to remain at least partly so until confronted to sophisticated state-building : until Roman times, a city is often associated to a particular tribe either dominant into a people, either part of it.
A person can say,I come from the Gaulish tribe Gx and so does three of neighbouring households.
A tribe isn't made up of households or families, but larger scale groups. What you're thinking of are either bands or clans.
Now, we have a lot of evidence of cities being identified with tribes up to the name of the city and the name of the tribe being the same. Either it's a kind of coincidence, either the differenciation tribe/city isn't nearly as radical you may think it is. Synoecism being fairly common in Ancient Med. you do end up with various tribal elements being mixed up. Thing is, it's nothing new : as said before tribes are a spontaneously unstable ensemble continuously redefining itself, loosing and including different groups over time. What happens in the process of urbanisation and synoecism isn't radically different.
Eventually, it's happening as such because the radical difference happened earlier during the transition between tribal societies as acephalic and achrematic socities, to chiefdoms (simple and complex) that are hierarchic and chrematic formations over the first ones. Urbanisation is only one feature of this transition which generally ends up with a new identity just as every group : Neroncens are issued from various pre-Celtic, Celtic and Iberized elements but considered themselves as one teuta, tribe. I think you may mix-up material culture, families/clan, tribes and chiefdoms there.
For most of Antiquity : a city = a tribe = a city(outside Gaul, you can see this with Athenian demoi) The growing disassociation came less from urban brassage eventually (as new comers are generally included) than state-building,with the people of one city becomes dominant politically over its sphere. Habitants of Latium became Romans not because they were "detribalized" or mixed-up, but because Rome came to dominate its hinterland, then beyond etc, making its identity dominant (even if not necessarily monopolizing). Basically state-building allows institutions to have a direct link with populations which tend to identify more and more with these rather than tribal identities. So, yes, cities such as Roman Ephesus aren't tribal but we're talking of a really, really long process that didn't even began to appear by the time we can still speak about PIE peoples and culture, or as it's the topic, Celtic meta-civilisations.
I'll leave at that, if you allow me, because I think we're talking in circles there.
Coming to Basque,I hypothesize that they are remnant of Neolithic Farmer communities originating in the Anatolia and Caucasus and looked bit like today's Basque and stretched over Europe,ME,NA,Iran and parts of Indian subcontinent with each speaking a language isolates or like that. Basque,Gutians,Hurro-Urartians,Minoans,Hattics,Sumerians,IVC people,etc might be of that ethnicity and origin itself.
This have nothing to really base itself on, even if it's regularily enough proposed since the XIXth century.
In all likeness, proto-Aquitains were already becoming an isolate in Late Neholitic, and possibly related to Mesolithic populations. There's literally no averred linguistic, genetic or material links between these cultures.
Not that Basques were isolated : there was a study in 2015 that would point a tie with early Neolithic populations. Of course, being genetics, it gives us next to nothing regarding culture (material or not), and is mostly identified with populations of Iberic peninsula which belong to different cultural groups as far as we can tell.
