Unia was formerly part of the German Empire. In the German Empire, the place was called Unnau.
The place is now called Unia and belongs to Poland.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Unia | German Empire | Wreschen | before the Versailles Treaty |
| Unia | Poland | Września | after the Versailles Treaty |
| Unnau | German Empire | Wreschen | 1939 |
| Unia | Poland | Słupca | 1945 |
| Unia | Poland | Konin | 1992 |