Actually, one of the key errors noted on my posting of the Piri Re'is map is rather uncanny circumstantial evidence that one of Re'is sources was
Columbus. Note how hispanola is turned on its side, 90 degrees. In Columbus' day, Japan was hardly known to Europe, but there was some vague
awareness of a long island off the coast of Asia. Columbus would have misrespresented Hispanola to back up his declaration (rather he believed it
himself or not) that he was in Asia. Furthermore, note the absence of Cuba on the map. Columbus made his crew swear that it was a promontory of the
mainland (probably because he wanted credit for finding the mainland).
Also, as I have said already, the notes in the margins of the Piri Re'is map make it clear that the charts of South America come from lost Portugese
sailors.
One of them, it turns out, may offer a clue to the accuracy of some parts of a map- perhaps explained by the skill of one man, although is not
absolute, as there are several factual errors (such as the number of ships Columbus originally had) in the margins.
And also Colombo was a great astronomer. The coasts and island on this map are taken from Colombo's map.
All of the notes on the map, translated:
www.prep.mcneese.edu...
The notes also make it clear that the maps which are from the time of Alexander the great are of the East, not the West.
The only really interesting gem, aside from the accuracy of the map itself, as that it claims Columbus had a book telling of a land to the west which
was full of ore. This of course is not at all unlikely, considering that Vinland was settled by the vikings circa 1000 and that Irish monks in Iceland
may well have reported on the new land in the west to the church.
It is in fact probable in my mind that Columbus did have some idea that he was going to unsettled land rather than Asia, and that he misrepresented
the new land as Asia for as long as he could to keep others from jumping at it, as he had demanded hereditary title as governor of all new lands he
discovered. His official story was seriously against the grain- he was undercutting the actual circumference of the Earth by more than half and
claimed that Asia and Europe spanned 225 degrees of the globe, making his claim of the distance between the Canary Island and Japan only 2,400
nautical miles. Of course since Eratosthenes had correctly calculated the earths circumference in the 2nd century BC this was a hard sell. The
Portugese turned him down for exactly this reason. I would even entertain the idea that the church might have stepped in and pressed Spain to take
Columbus up. Ferdinand and Isabella were both devout Catholics afterall, and with the overland route to the Indies blocked by the Muslims, whichever
nation either found a sea route or found an alternative trading partner would have been very powerful. For some reason the Vatican seemed to favor
Castile. Not long before Columbus' time the church had changed its mind about recognition of Portugese possession of the Canaries, and instead
recognized Castile.
So there is my take on things basically. No highly advanced ancient civilizations, just a very lucky sailor who happened to hear a few things in his
trip to Iceland and later recieved many Portugese charts as a dowry when he married the daughter of a Portugese nobleman, and subsequently talked
Castile and Aragon into backing him, quite possibly because the Catholic church knew there was something out there courtesy of monks in Iceland.