Seems like they would have found metal pieces or remnants of crafts built 3000
to 5000 years ago by now. Or at least they would have found their version of
the "Lockheed Skunk Works" as it would have required huge factories to build
and maintain them.
The Vamana descriptions are very intriguing when analysed in terms of modern
technology...but so are Jules Verne's ideas from the 1800's whose descriptions
of modern technology were quite prescient.
Perhaps they were following the "prime directive" and made sure to clean up
after themselves.
I wonder if MMY ever discussed these "fables"?