http://www.etymonline.com/index.php?term=silk

O.E. sioloc, seoloc "silk," ultimately from an Asian word (cf. Chinese si "silk," Manchurian sirghe, Mongolian sirkek) borrowed into Gk. as serikos "silken," serikon "silk" (cf. Gk. Seres, a name for an oriental people from whom the Greeks got silk). The use of -l- instead of -r- in the Balto-Slavic form of the word (cf. O.C.S. shelku, Lith. silkai) apparently passed into English via the Baltic trade and may reflect a Chinese dialectal form, or a Slavic alteration of the Greek word. Also found in O.N. silki but not elsewhere in Germanic. Western cultivation began 552 C.E., when agents from Byzantium impersonating monks smuggled silkworms and mulberry leaves out of China. In reference to the "hair" of corn, 1660s, Amer.Eng. Figurative use of silk-stocking (adj.) for "wealthy" is attested from 1798, Amer.Eng. Silk-screen is first attested 1930. Silk road so called in English from 1931.