Everybody keeps pointing at Angus as the source of black hide... but y'all are disregarding all the other black cows that might be way back behind animals in a breed that allows 'breeding up', with an open herdbook.
My first 'black' Simmental crosses - bred back in the late 80s - got their black haircoat from Holsteins and a little black Jersey-cross cow. For decades, I had black SM-influenced cattle with little to no Angus anywhere back in their ancestry.
There was a large dairy in the county where I practiced that was owned by a Simmental breeders corporation that was using the HO cows as recips and running SM bulls for cleanup... quite a few black SMxHO calves came out of that deal, and probably made their way into the SM herdbook as halfbloods...with no Angus in the equation
Black Simmentals are Simmentals, not Angus.
Cg8, I can show you photos of 100% fullblood Fleckvieh Simmentals that are solid red...not a speck of white. You can get there with selective breeding. Just like the SM breeders have addressed CED, BW, frame score, etc. ... selecting for it in making one's breeding choices.