People would follow the silk road sometimes. Rome actually had limited diplomatic contact with China, even. That's not on the map, maybe because they didn't really understand where it was, besides somewhere far to the east. I'm surprised SE Asia is on it, I'll have to do some reading about that, but India was known even to the Greeks.

Quality of information would drop off really rapidly with distance, though, since it was easy to make up a fish tale about what you saw in far-off lands. So, you find a lot of crazy BS mixed in with helpful nuggets in things like Herodotus's Histories.