Grand Pyrnees. Traditional sheephearding dogs.
Sheep herding dogs are agressive by nature. They are working dogs.
To tell you the truth I knew that but it wasn’t so in the 30s 40s and 50s when I was growing up the the San Joaquin valley as the imported Basque sheep herders used... sheep dogs
Great Pyrnenees are not herding dogs. They are protection dogs. My dogs are Belgian Malinois, and this breed is a true herding dog.
Neither animal guard dogs, nor herding dogs are aggressive, unless their charges are being attacked. People have so many beliefs that just are not factual!
I have tried to explain endlessly to my sis that the reason my Belgian Malinois are not “friendly” to her lag and golden is that they are bred to be stand-offish and aloof to other dogs, for the reasons some have stated above. Other dogs can “run” the sheep, chase the chickens, etc...
Herding and protection dogs are supposed to keep varmints of any kind away. Any who were overly friendly to strangers of any kind (animal or human) were not used for breeding, as friendliness wasn’t a helpful trait.
There is a difference between a dog being aloof/stand-offish, and a dog being aggressive. An overly aggressive working dog would also be quickly culled from the bloodlines of good working dogs.