There are few archaeological evidences on the Solar Tribes.
We know that "Solar Tribes " is how they call themselves, it was only used by the other tribes around

"Solar" does not indicate a specially close relation with the Sun of our solar system :
they do love and respect and even occasionally worship the Sun, but for sure no more then the many other Tribal group around,
it refers to the Inner Sun at the core of our planet and to all his manifestation, as geysers and volcanic eruptions

They live almost in symbiosis with Volcano , very close to the open flaming cone and at soon their Shaman in his dream received the Volcano 's invite , they move in

Obviously most of Shamans were tricksters, yet even now the science could not explain how they could make such accurate previsions of volcanic activities

In the beginning of the knew history of the tribe volcanoes were more active more frequent and powerful explosion , lethal not only for the quantity of Lava and the sizes and speed of the projected rocks, or the expanding clouds of poisonous gas , but for the amplitude of the waves of pyroclastic flow that could incinerate and everything for hundreds , even thousand of miles around...sucking all oxygen out the air in the passages

But in cases the Shaman had a Dream , the Vulcan kindly suggesting him and all of the Shaman tribe to leave for holidays, and and even explaining the best route for a nice and cool place to go, and for how long would be better stay there

The place where usually close-by beach of subterranean lakes or rivers, much much below the surface :
OUTSIDE for hundreds thousand miles would be no hope to survive to the sulphuric gases and to the pyroclastic flows , and in a much , much wider area would be even hard to survive to the Darkness and the frozen cold , because the dark depth layers of black clouds , clouds of gas and ashes that would block the sun rays, for days , weeks even more.

It was clearly better follow the Vulcan suggestion, go with plenty of provisions depth below to camp around a subterranean lake was Not only was surely nicer then roast or suffocate outside , but the usually icy waters of the subterranean stream now where at the best temperature for bathing, hot as around tropical islands, even a bit more

To make the history short the Solar Tribes survived pretty well to the Ice Age, they never developed a technology as we intend, yet they become soon Master of the art of Dwell Carving , in a later period they even did some course to teach some apprentice the basic of dwell carving
All Solar Tribe Shamans were sufficiently sensitive to consider very carefully the Vulcan ' suggestions so the Solar Tribes survived till now, even if they tried to remove the evidence and went underground

That because the Shaman had a dream, almost a nightmare , it was very confused , it was a evil conspiracy on a too large scale for his mind to grasp , but outside soon would be no more tribes but States , and States will impose not only material tributes , but will impose "religions " with "Priest" "Monk" and "Nun" instead then Shaman...the old Shaman would be taken and roasted first, then the other with doubts on the new religion would follow ...

And then was the VOICE of the Vulcan ... not really a Voice each word not only a sound but also flashing images and smells and vibrations ... but the main concept of the was crystal clear as
...
"My beloved friends i always protected you with my suggestions
even when my Fire was so intense that i could hardly control , even then before let it go i always find for you a safe shelter

, even surrounded by Fires so warm to melt the rocks , i always assure you a fresh breeze and cool place to camp and party

Now , do you prefer you and all Tribe enslaved or roasted alive, roasted by ridiculously little fires, yes sufficient to kill , slowly and with the most intense agony ? From that stupid little fires i could not protect you... even if are nothing compared my Fire yet out of my control

Or you prefer consider my suggestion ... "

A heartbeat later the Shaman awakened, and no much later all the Solar Tribes went underground so depth that they was never found (but you may imagine the shore of subterranean lakes, with little friendly geysers for saunas and steam cooking, fresh current air from somewhere and the best mushrooms and truffles all around )

Now the only evidence left the whispered myth,

and a few decorative patterns found on top of the Etna, when tumbling down the opening of tunnel ,
alas filled and sealed by the magma of a later volcanic eruption