Yeah, I’m kinda afraid that’s the case. I wish more info were available (and research were done) regarding Roman-era (and earlier) seagoing contact with China. The Han court records contain reference to receiving a Roman envoy (probably a merchant) from the court of Marcus Aurelius, and the Chinese sent an expedition to the Persian Gulf just a few years after Trajan’s death (basically, it happened during the reign of Hadrian I believe).
I’m sure there were contacts in ancient times, quite possibly many and regular contacts along the (Indian Ocean) coast. But what we actually know, isn’t enough to fill a bookmark, never mind a book.