JP Sauer has been around for years. They are made in various quality levels but overall are quality guns, even the lower models. If you google the history of JP Sauer, you will get some info. I know after the wall came up in Germany things changed a little. Sauer, Merkel and Simson were then all produced in the same plant under control of the East German government. There was little difference amongst the names. But my knowledge is sketchy on this.
I did however just pick up a very nice Sauer from a forum member. It has engravings of upland birds on one side and geese on the other. It was made in 1963 and appears almost as new.
I also have a Sauer sidelock drilling from 1909. It is a very well made gun. Downside is, someone removed the bottom rifle barrel on it.