The Vulcans and Ancient EarthTo preface this, I'd like to point out that I don't give Erich von Däniken's theories about alien influence on ancient human society any credence in real life, however, in the "reality" of Trek they would fit in quite well with other accounts of aliens landing on Earth and influencing both human genetics and culture for billions of years.
While this isn't a fully developed theory as of yet (I have more thoughts on the mythology of Earth and alien cultures that I have to condense into one unifying theory), I'd just like to put it out there as a fun thing to consider.
Anyway, here are some images and maps of the Nazca Lines in Peru: http://en.wikipedia.org/wiki/Nazca_lines.
Von Däniken theorized in his book "Chariots of the Gods" that the Nazca Lines were used as "runways" or landing patterns for ancient spacecraft, as well as symbols of worship of those alien "gods."
Now, contrast this with these scenes from ST:IV and Voyager that show the massive plateau at Mt. Seleya on Vulcan:
The commonalities in their appearance are remarkable. Especially so when we consider that the lines in ST:IV were basically being used as a landing zone for spacecraft visiting the temples of Mt. Seleya, as well as possibly having some other religious significance from ancient Vulcan culture.
Also notice that the most prominent symbol surrounding the "runway" patterns is a large bird reminiscent of the Romulan raptor (you can also see it in the Nazca photo collage above):
Obviously the two planets would not have been in their symbol back then because they had not yet settled on Romulus and Remus, but we do know that they used the raptor as a symbol from as far back as at least Surak's era from the Enterprise Vulcan arc where Surak called the soon to be Romulans "those who march beneath the raptor's wings."
We know that Vulcans and their Romulan offshoots had interstellar capability from at least as far back as 850 BC when the monastery on P'Jem was constructed near Andorian space. The Nazca lines were constructed between 200 BC and 700 AD, well within any interstellar exploration period for the Vulcans.
If the Vulcans or Romulans were to temporarily settle in various areas of Earth the Nazca Desert would make a perfect choice due to its remoteness and similarity to their native Vulcan climate and religious center of Mt Seleya.
Also consider that the Roman mythology that influenced both the name and culture of Vulcans and Romulans (Vulcan, Romulus, Remus, Praetor, Centurions, the Senate, et. al.) was also at its height during this same era.
Other Earth cultures either influenced or were influenced by aliens during roughly the same time period and earlier, including Apollo and his cohorts being the inspiration for the Greek "Olympians," and the Sahndaran refugees settling in Greece and being inspired by the philosophy of Plato and becoming the Platonians, amongst others.
Perhaps the Roman people of planet 892-IV in TOS: "Bread and Circuses" weren't a product of Hodgkin's Law of Parallel Planet Development but rather Roman slaves transported to a new planet by their Vulcan / Romulan masters, a planet outwardly similar to Earth that they terraformed until conditions and appearance was identical to Earth (this is kind of far-fetched I know, but I always hated the whole "parallel planet" nonsense that was used as an excuse for simply filming normal Earth / Human scenes - the only other thing I could think of that would work was maybe an Earth from a parallel universe was pulled through subspace into our universe like that planet in DS9: "Meridian").
Given Vulcan's repeated missions to study Earth culture in both canon and novels, I think it would be reasonable to assume that they might have established a concealed colony on in the Nazca Desert in Peru on Earth around 2,000 years ago, studying Earth culture, perhaps taking some slaves or servants, and also adopting certain aspects of Earth culture (not unusual for a dominant or conquering group to do) as their own. Then when their time was done (perhaps during the Time of Awakening) they abandoned their colony and removed all trace of their being here so as not to influence Earth cultural development. Anyone who had contact with them would have been taken with them, like perhaps some of the Nazca people and Romans.
(Theory by Bond, James Bond)