Do note that red, yellow, green, and blue are the four “unique hues” which anchor human color perception. All other hues can be described as a combination of two of those (for instance orange is yellow–red, or purple is red–blue). You might call RYGB the “primary colors” of human color vision, as compared to the primary colors of some particular medium like RGB {orangish red, yellowish green, reddish blue} for computer displays or CMYK {greenish blue, bluish red, yellow, black} for printers.
One of the first couple stages of neural processing of color, which happens directly in the retina, is a compression/interpretation of 3 cone cell responses into 3 “opponent” color signals: blue–yellow, red–green, and white–black.
As a result, there’s plenty of artwork dominated by red/yellow/green/blue dating back thousands of years.
