May I suggest you look at a few books by Chase-Dunn  and Hall.  I
believe that you may find reference to what you are looking for within
there text.  I am not sure how familiar you are with World Systems theory
so I would suggest you start with that.  Many archaeologists work within
it to show not trade routes but the deviations from the known route.  You
may also want to look at frontier models for trade.  Unfortunately I am
in the field right now and do not have that reference.

Good luck
Dan

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