Well, actually, the Vikings probably post date Islam. However, there are plenty of earlier possibilities. My guess is the Sea Peoples around 1200 to 1400 BC. Black mercenary soldiers were apparently being used by various poeples in that period. My guess is that one or more ships carrying a mixed crew of middle easterners and black soldiers was stranded along the Mexico coast. The black mercenaries took over and that is why we have Negroid Olmec heads and a flourishing of Olmec architecture.
The Vikings’ first recorded raid (outside of Scandinavia that is) is circa 790 (late 8th c), or about two centuries after Mohammed, and the Varangians didn’t show up in Constantinople until the 9th c, but there’s no indication that the Muzzies ever made it to the New World except for black African Moslems captured and enslaved by fellow Moslems (often Arabs) and sold to the Portugeuse, Spanish, Dutch, French, and English as New World colonial labor.
And of course, the Americas were crammed full of people for thousands of years before Mohammed’s bastard birth, as well as before the Vikings, the Celts, pharaonic Egyptians, etc etc might have crossed the Atlantic. Somewhere around FR someone posted the surviving Roman account of an apparent canoe full of Native Americans paddling up to the port of Ostia.
Roman-era amphorae, from a Roman wreck off Brazil now off-limits to divers:
http://www.faculty.ucr.edu/~legneref/ethnic/jpg/fig76.jpg
‘Civ quibble of the day: the Sea Peoples didn’t exist per se, and the activities attributed to them took place much later than 1200 BC.
Circa 7000 years ago, the Red Paint People (or perhaps someone else, with the Red Paints coming along a little later) left characteristic traces of themselves throughout coastal and Arctic Canada as well as Arctic Eurasia.
Human activity in the Americas is wonderfully old, and far exceeds the glass floor constructed by Clovis-First-and-Only. McWhorter refers to the linguistic diversity (indicating either waves of unrelated settlement, or long periods of isolated development, or both) of South American PreColumbian groups as “a delirious, kaleidoscopic riot”.
