The colour yellow is made from a natural ochre mineral.

Yellow too is one of the oldest colours in the world. And it too was used in prehistoric times in cave paintings well over 17,000 years ago.
It is prevalent in the oldest paintings dating back to Egypt and ancient Rome.

Because yellow is associated with the sun it is considered a warm colour. It was a favourite colour with Van Gogh. (Sunflower paintings)

An artificial substitute for yellow ochre was found in 1920.

Today, because yellow is an arresting colour it’s often used as a key colour for emergency vehicles; ambulances and taxis.