I remember reading in Roman History class back in college that during the reign of Emperor Trajan (r. 98-117 AD), the Roman Empire sent an emissary to China. This information was found not in Roman records, but Chinese. Now there's some archaeological evidence to support the historical claim of direct Roman-Chinese contact. The remains of a man with East Asian genes from 2,000 years ago has turned up in southern Italy:
Link | Photo: Indiana University
Researchers found his body on an imperial Roman estate and took dental samples. Why examine teeth? Well, the water you drink at birth leaves a distinct signature in your teeth. That water signature is in the form of oxygen isotopes, atoms of oxygen with different numbers of neutrons. Isotopes say something about the latitude and elevation of your birthplace—which in the case of our mystery man definitely wasn’t southern Italy.
Then the researchers tested his mitochondrial DNA, which is passed down through your maternal lineage. And this fellow had east Asian genes.
Link | Photo: Indiana University
Also, I wouldn't be concerned about the water. None of the water we drink is %100 H2O. We'd be pretty sorry if it was. It's just different depending on the wheather, soil, and society.
This should come as no surprise, really. There were very ancient trade routes way before that.