I had one back in the '70s. Chinese temple guard dogs...they are tough, you are correct. We named her Shao Lin. And I know they are supposed to be stupid, but I guess ours never read the instructions, since she was reasonably intelligent.
Mine is stubborn as a mule, and even a 3 months, very territorial and ready to attack when someone comes to the door..........
Guess mine didn't either. He catches on quick. He can be stubborn sometimes. He's energetic & fast. Very fast.