Yellow was easy to obtain and difficult to obtain well, and the gap between the two is the reason the colour carries such divided associations.
At the cheap end are yellow ochres, iron-bearing earths that need only grinding, available everywhere. At the expensive end are pigments that were genuinely hard to get. Orpiment, arsenic trisulphide, gives a golden yellow so like gold that it was called auripigmentum, and it is acutely poisonous. Saffron, the stigmas of a crocus harvested by hand, has always been among the costliest agricultural products in the world. Gamboge, a resin from Southeast Asian trees, reached Europe as a trade good.
Indian yellow is the pigment with the most repeated origin story and the least secure one. It is usually said to have been made from the urine of cattle fed on mango leaves, an account that circulated in nineteenth century British sources and that later scholarship has questioned without settling. The atlas records the claim as a claim.
For textiles, weld and dyer's broom gave reliable yellows cheaply, which meant yellow cloth was ordinary. That is the root of the colour's second reputation in medieval Europe, where yellow was assigned to the marked and the excluded, to Judas in painting and to compulsory badges in law, at the same time as gold and saffron stood for the highest honour. One colour, two economies, and two entirely opposed sets of meanings running side by side.