Nope, seagoing Roman trade with China (as well as possible overland “silk road” traffic) went on, and in at least one case was documented in China, a Han court record which lists the correct emperor for the year in which the reference was made. Also, the Chinese sent an ambassador and trade expedition to the Persian Gulf, and just missed the Romans (the occupation of Mesopotamia only lasted a year or two; Trajan conquered it, died, and Hadrian decided to drop it).
Archeologists discover ancient graffiti on China’s Great Wall
Yahoo News | July 11, 2004 | AFP
Posted on 07/11/2004 7:17:46 PM EDT by FairOpinion
http://www.freerepublic.com/focus/f-news/1169415/posts
Romans in China?
Archaeology | Volume 52 Number 3, May/June 1999 | Erling Hoh
Posted on 07/18/2004 11:43:09 PM EDT by SunkenCiv
http://www.freerepublic.com/focus/f-chat/1173944/posts
Roman Legion Founded Chinese City
Ansa | 7-25-2005
Posted on 07/31/2005 12:31:23 PM PDT by blam
http://www.freerepublic.com/focus/news/1454296/posts
Roman Descendants Found In China?
The Telegraph (UK) | 2-2-2007 | Richard Spencer
Posted on 02/01/2007 9:08:49 PM EST by blam
http://www.freerepublic.com/focus/f-news/1777711/posts