Sobaka and Iranian

Piotr
<<My idea is that <sobaka> was borrowed from a source that had something like
*s&baka -- not into Proto-Slavic but into relatively late East Slavic... The
weakness of this hypothesis is that I can't identify the intermediary between
Iranian and Slavic.>>

I'm curious about the need to identify an intermediary between Iranian and
Slavic. Herodotus writes of "Indian dogs" among Greeks, presumably the result
of long-distance trade in breeds of canines. The hoards of Arab coins found
in West Slavic settlements from as early as @800AD would suggest extensives
trade contact with the East over an even longer distance than Eastern Slavic
would present. Is there a reason we can't assume this might be a trade name,
introduced by Iranian-speaking traders? I'm just asking if you are limiting
"contact" to proximity or you have some specific reason to think that Iranian
speakers could not have been in contact with Eastern Slavic speakers? (BTW,
how would the word - as a trade name for a trade object - have changed if it
had come through something like Armenian?)

Regards,
Steve Long