Stirpes: Rome "a new kind of city"

What we've seen in Metamorphoses 14 is, in part, a developing sense of what Romans are, and what they are not. What they are not, to come right to it, is Greeks, Phrygians, Carthaginians, or Sicilians. It's harder to say what they are. 

The merger of the Trojans and the Latins in the marriage of Aeneas and Lavinia, daughter of Evander, is a key moment in the genealogy of Romanness, but why?

To probe this key fellow Evander is to find a culture hero who brought gods, laws and letters of the Latin alphabet to Italy from his home of Pallantium in Arcadia. He knew letters from Carmenta, his mother, who is the chief of the four nymphs known as the Camenae. The spot where Canens, lamenting Picus, dissolved into the Tiber became associated with the Camenae, blending a kind of Orphic power (Canens < cano) into the river where the Roman Muses dwell.

The initial encounter of Aeneas and Evander is rich in mythological resonance in book 8 of the Aeneid. Evander founded his city, Pallanteum, 60 years before the Trojan War, on the site of what would become Rome. Here's a small bit of Kline's translation:

The king walked clothed with years, and kept Aeneas and his son
near him for company, lightening the road with various talk.
Aeneas marvelled, and scanned his eyes about
eagerly, captivated by the place, and delighted
to enquire about and learn each tale of the men of old.
So King Evander, founder of Rome’s citadel, said:
‘The local Nymphs and Fauns once lived in these groves,
and a race of men born of trees with tough timber,
who had no laws or culture, and didn’t know how
to yoke oxen or gather wealth, or lay aside a store,
but the branches fed them, and the hunter’s wild fare.
Saturn was the first to come down from heavenly Olympus,
fleeing Jove’s weapons, and exiled from his lost realm.
He gathered together the untaught race, scattered among
the hills, and gave them laws, and chose to call it Latium,
from latere, ‘to hide’, since he had hidden in safety on these shores.
Under his reign was the Golden Age men speak of:
in such tranquil peace did he rule the nations,
until little by little an inferior, tarnished age succeeded,
with war’s madness, and desire for possessions.
Then the Ausonian bands came, and the Siconian tribes,
while Saturn’s land of Latium often laid aside her name:
then the kings, and savage Thybris, of vast bulk,
after whom we Italians call our river by the name
of Tiber: the ancient Albula has lost her true name.
As for me, exiled from my country and seeking
the limits of the ocean, all-powerful Chance,
and inescapable fate, settled me in this place,
driven on by my mother the Nymph Carmentis’s
dire warnings, and my guardian god Apollo.’

Here's an interesting passage from the 19th c. French historian Fustel de Coulanges, pondering all this:

The origin of Rome and the composition of its people are worthy of remark. They explain the particular character of its policy, and the exceptional part that fell to it from the beginning in the midst of other cities. The Roman race was strangely mixed. The principal element was Latin, and originally from Alba; but these Albans themselves, according to traditions which no criticism authorizes us to reject, were composed of two associated, but not confounded, populations. One was the aboriginal race, real Latins. The other was of foreign origin, and was said to have come from Troy with Aeneas, the priest-founder; . . .. [Big snip in which Hercules and more races are mixed in] Rome did not seem to be a single city; it appeared like a confederation of several cities, each one of which was attached by its origin to another confederation. It was the centre where the Latins, Etruscans, Sabellians, and Greeks met. The Ancient City, p. 311.