The East had a monopoly on this material until the 6th century, when 2 monks smuggled out some worms
.... By the sixth century the Persians, too, had mastered the art of silk 
weaving,... [DOC] [TLE] Smuggling of silkworm eggs into the Byzantine Empire - Wikipedia [PAR] In the mid-6th century AD, two monks, with the support of the Byzantine emperor 
Justinian I, successfully smuggled silkworm eggs into the Byzantine Empire, 
which led to the establishment of an indigenous Byzantine silk industry.