Large Swiss Mountain Dogs have never been overly popular dogs, but it is also impossible to call them little known. The calmness and strength of these beauties always attracts people to them, who value in dogs not external glamor, but reliability and solidity
This is a completely justified version, since the path from Rome to Germany ran directly through the territory of modern Switzerland, and in military campaigns, the Romans were always accompanied by large fighting dogs. These dogs belonged to the group of mastiffs, and they could mingle with the local mountain shepherd dogs.
It is in this similarity that they find an explanation for the good-natured disposition of the Sennenhund - dogs, not warriors, but shepherds.