Saffron slowly propagated throughout much of Eurasia and was later brought to parts of North Africa, North America, and Oceania. Saffron was detailed in a 7th-century BC Assyrian botanical reference compiled under Ashurbanipal. Documentation of saffron's use over the span of 3,500 years has been uncovered. Saffron-based pigments have indeed been found in 50,000-year-old depictions of prehistoric places in northwest Iran. The Sumerians later used wild-growing saffron in their remedies and magical potions. Saffron was an article of long-distance trade before the Minoan palace culture's 2nd millennium BC peak. Ancient Persians cultivated Persian saffron ("Crocus sativus" 'Hausknechtii') in Derbent, Isfahan, and
Saffron bun areas and by Swedish-speaking Finns, as well as in Norway and more rarely in Denmark. Most commercially available saffron buns and cakes today contain food dyes that enhance the natural yellow provided by saffron. The very high cost of saffron - the world's most expensive spice by weight - makes the inclusion of sufficient saffron to produce a rich colour an uneconomical option. The addition of food colouring in Cornish saffron buns was already common by the end of the First World War when the scarcity of saffron tempted bakers to find other ways to colour their products. Saffron bun