The Arabian Horse Association registers purebred horses with the coat colors bay, gray, chestnut, black, and roan. Bay, gray and chestnut are the most common; black is less common. The classic roan gene does not appear to exist in Arabians; rather, Arabians registered by breeders as "roan" are usually expressing rabicano or, sometimes, sabino patterns with roan features. All Arabians, no matter their coat color, have black skin, except under white markings. Black skin provided protection from the intense desert sun.