Okay, you look at a map like this, and you wonder: given that it was clearly physically possible, did anyone actually *go* on the trade routes from the coast of China all the way to Britain?
Maybe he could be some rugged, Conan-like dude from the savage remnants of Boadicea's defeated army, and he'd think: given that the Romans have kicked our ass, why don't I venture across the water and find out who these people are? And then he just *doesn't stop.* Not till he's knee-deep in the Pacific, and then he contemplates Japan and decides, "no, not worth it."
One can easily imagine some attractive Chinese girl being bundled up as basically trade-goods, and then being manhandled, kidnapped and human-smuggled from empire to empire until some tender-hearted legionary sets her up with her own flat in Londinium.
Even if people didn't make it, there must surely have been *stuff* that made it. Silk and tin would have been pretty obvious, but maybe *other stuff.* Maybe really *weird* stuff.
