You may run across a piano labeled "Steinweg". The Steinweg family manufactured pianos in Germany (what became later East Germany). Heinrich Steinweg (or better known as "Henry Steinway") left for the U.S. during the industrial revolution, where, as mentioned in an earlier post, he built the current Steinway & Sons company in New York. Later, another factory was added in Hamburg by the same company. Though the name is of German origin, the anglicized Steinway & Sons name is also being used for the Hamburg factory.
The original Steinweg company continued to produce pianos on their own, but were not in any way associated with the new company based in New York. When the East opened up, Steinweg rebranded their pianos as "Grotian". So when you see a Grotian, it is from the factory of the same family that Henry Steinway came from back in the 1800's, but is not in any way associated.
My piano technician told me a funny anecdote: He was at this person's house, and was tuning a Steinweg. The owner looked at him and said that this was a German Steinway. He said to her no, it wasn't, and she told him yes it was, he did not know anything about pianos, AND THREW HIM OUT OF THE HOUSE! Apparently a salesperson had convinced her she was buying a German Steinway!