06-06-2012, 08:47 AM
From a quick google search, it appears that is a bit of a fringe theory. Roughly there are lots of theories about contact with the Americas from Europe and Asia. In general there are a couple confirmed contacts, one from Europe (the Vikings) and one from Asia (the Polynesians) that predated Columbus, then there are theories supported by very small amounts of evidence, but the evidence is at least somewhat credible, there just isn't enough of it to be convincing, and then lastly you have the more fringe theories that have no evidence to support it, or evidence that has to be interpreted in a non-mainstream way to support a contact with the Americas and the Muslims discovering America theory I think falls into that last catagory. There are writings that predate Columbus that mention expeditions to foreign lands, but the mainstream interpretation of those documents among the historical community is that they are actually referring to Europe.