There is another fact I would like to emphasize here: Almost all of "North Western Iranian/Persian" labeled rugs are South Azerbaijan rugs. It shouldn't be understood as an ethnic discrimination towards Persians, but it is scientifically wrong to call South Azerbaijan rugs as "Persian rugs".
The Greek historian Xenop-hon (Vth century B.C.) reports that Persians learned to use carpets from the Modes (He means Meds, who is considered as the ancestors of present day Azeris.)
