What I thought Sargon meant with all that pompous flowery talk is that his people made a colony on Vulcan, and that eventually went native and became the Vulcans. Of course it only takes 20 thousand years for all evidence of a civilization to vanish, so the Vulcans could have been space faring, devolved to barbarism, got back civilization again and then lost it again and again and again, which is why embracing logic was such a special idea, because in theory it put an end to that cycle of destruction, amnesia and rebirth they were so good at.
Spock called 1/2 a million years "prehistory" not dinosaur times, which suggests that Vulcans then looked a lot like Vulcans now and must be from somewhere entirely else, which hints that Sargon's lot had not poured barrels of space jizz into the oceans hoping that billions of years later that those building blocks... Well it was only 500 millennia wasn't it, which is the tenth of the time necessary for a single celled life form would need to transform into a tool using humanoid.
Do we count our history starting from Greece and Rome, or from Italy and the Renaissance? The Dark Ages should really be a border between two sets of histories of man, since on either side of that border the dominant cultures were very different. If the dark ages had lasted another 500 years, maybe we would have no idea about the Roman Empire at it's Height?
(Yes, the Eastern Roman Empire was around till the 14th century when the Turk sacked Constantinople, it was only the Western Roman Empire that fell to the Goth in the 4th century. Hush.)