Rejna was formerly part of the German Empire. In the German Empire, the place was called Reinau.
The place is now called Rejna and belongs to Poland.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Reinau | German Empire | Inowrazlaw | before the Versailles Treaty |
| Rejna | Poland | Inowrocław | after the Versailles Treaty |
| Reinau | German Empire | Hohensalza | 1939 |
| Rejna | Poland | Inowrocław | 1945 |
| Rejna | Poland | Bydgoszcz | 1992 |