Among all the different tags which may be found on the back of a hand knotted carpet, the one that always seems to excite the most is one which reads: "Made in Persia"
Although there are tactics less reputable dealers have been known to exploit, there's relatively little upside to a seller who is interested in long-term sustainability to forge such information. Generally, these tags can be trusted as being true to origin to a certain extent:
While it would make sense a rug with a tag stating 'made in Persia' may have the connotation the rug was made pre-Iran (internationally recognized post 1935), this is not always the case. Tags stating 'made in Persia' seen affixed to hand knotted rugs and carpets continued to be made and sewn to the backs of rugs beyond 1935. Despite what deductions one may make based upon the interchangeability of 'Persia/Persian' and 'Iran', the presence of such a tag does not serve as an accurate indicator of age, nor does it indicate a superior rug or carpet.