The oldest clear evidence for saffron is on Thera. The frescoes at Akrotiri, buried by the eruption around 1600 BCE, show women picking crocus flowers and presenting the stigmas to a seated goddess, with a monkey handing baskets up to her. It is an unusually explicit depiction of a harvest as a religious act, and it establishes both the crop and its ritual use in the Bronze Age Aegean.
Iran now produces the overwhelming majority of the world crop, roughly ninety percent, concentrated in Khorasan. Kashmir, Afghanistan, Morocco, Spain, Greece and Italy make up most of the rest. Sanctions and export routing mean a substantial share of Iranian saffron reaches consumers labelled as Spanish, which is a long-standing and well documented practice in the trade.
Adulteration is old and constant. Safflower, turmeric, dyed maize silk and shredded paper have all been sold as saffron, and medieval Nuremberg burned adulterators at the stake under the Safranschou code, which indicates both the scale of the problem and the value of the product.
The labour is the cost. Picking is done before the sun opens the flowers, the stigmas are separated by hand the same day, and the work is seasonal, poorly paid and largely done by women. That has not changed in three and a half thousand years.