[SeekAndFind]

RE: THAT plague came from China as well.

Did the western world already have contact with China in 166 AD?

[wrcase]

Probably came through India and Persia. Rome just finished one of many wars with Persia.

[cloudmountain]

Did the western world already have contact with China in 166 AD?
YES. See below.

Google

The first group of people claiming to be an ambassadorial mission of Romans to China was recorded as having arrived in 166 AD by the Book of the Later Han.

The Roman mission came from the south (therefore probably by sea), entering China by the frontier of Rinan or Tonkin (present-day Vietnam).