Would combining dogs from different countries necessarily create a mutt?

when I asked could cross of sarmatian mastiff dogo belgrado and wolf create a breed everyone said no way no how ok putting wolf together with a guard dog might not be a best idea. However when they design dogs they put all kinds of dogs together at least that what it seems. And Just because dogs come from different countries does not mean they can't be bred together. I wonder if Amdo mastiff, Himalayan Mastiff and Rottweiler could create a breed or at least a ban dog. Why would I want to cross them together. Amdo for strength, Himalayan for size and rotweiler for intelligence. could this be a breed or a ban dog or would it definitly be another mutt