Why does the Chinese source describe the Da-Qins (ancient Romans) as having silkworms? Weren’t these a much later import to Rome during the early medieval era?
A couple of Christian monks smuggled out silkworm eggs to Constantinople during the reign of Justinian I. Before that the Romans had no silk production. But they imported silk from China, reworked it, and re-exported the improved cloth back to China, leading the Chinese to think that the Romans had a supply of silk.
Possibly just a bum report from one of the ancient writer's sources -- but it may have been silk, or one of the alternative silk types and this is the only record of it. The Indus Valley civ had silk around the same time as the Neolithic Chinese, but it wasn't the same source (they used silk moths).