Professor Chen: in the early Middle Ages, there was no trade between Europe and East Asia, because there were no written records in the existing archives  Researcher Li: your argument is similar to this one: the legendary Himalayan Snowman does not exist, because no one has ever witnessed this kind of snowman
The problem with this argument is that someone who sees a snowman can certainly prove that the snowman exists, but no one can't prove that the snowman does not exist
Despite the lack of reliable written records, trade between Europe and East Asia was very likely in the early Middle Ages.