Mrotschen was formerly part of the German Empire. In the German Empire, the place was called Immenheim.
The place is now called Mrocza and belongs to Poland.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Mrotschen | German Empire | Wirsitz | before the Versailles Treaty |
| Mrocza | Poland | Wyrzysk | after the Versailles Treaty |
| Immenheim | German Empire | Wirsitz | 1939 |
| Mrocza | Poland | Wyrzysk | 1945 |
| Mrocza | Poland | Bydgoszcz | 1992 |