Saffron (trade) by far the world's most important producer: in 2005 it grossed some of dry threads, or 93.7 percent of the year's global total mass; much of the Iranian crop was bound for export. Northeasterly Khorasan Province, which in 2004 was divided in three, grows 95 percent of Iranian saffron: the hinterlands of Birjand, Ghayen, Ferdows in South Khorasan Province, along with areas abutting Gonabad and Torbat-e Heydarieh in Razavi Khorasan Province, are its key cropping areas. During 2004, Iran was not a member of the World Trade Organization. and still until November 2009, Iran was again not a member of
Saffron per gram, given the wide possible range of colouring strengths that different kinds of saffron can have. Despite attempts at quality control and standardisation, an extensive history of saffron adulteration, particularly among the cheapest grades, continues into modern times. Adulteration was first documented in Europe's Middle Ages, when those found selling adulterated saffron were executed under the "Safranschou" code. Typical methods include mixing in extraneous substances like beetroot, pomegranate fibres, red-dyed silk fibres, or the saffron crocus's tasteless and odourless yellow stamens. Other methods included dousing saffron fibres with viscid substances like honey or vegetable oil to increase their weight.