> If so, what maritime culture might have played the key
> transport role?
The Atlanteans, of course. :)
Only kidding, Lew.
On a serious note, you need to do some more homework on this tobacco and coca in Ancient Egypt business.
It has, apparently, been refuted by mainstream Egyptology.
A session with Google should fill in the gaps in your knowledge.
As for the source of the Incas' gold; why look as far afield as Southern Africa when it was a lot easier to just nip along to, for example, what is now known as the Rio Huaypetue mine, a large open-pit gold mine in south-eastern Peru, inside the Cusco Region.
Have you considered the likelihood that the disc to which you refer could have been gold plated?
* close to the border with the Madre de Dios and Puno regions. It has been estimated that at the peak of production in 1998, some 2 percent of the world's annual gold production may have come from Huaypetue.
Oh, where would we be without Google and Wikipedia?
So few answers - and not one of them mine.