Ustronie was formerly part of the German Empire. In the German Empire, the place was called Seitendorf.
The place is now called Ustronie and belongs to Poland.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Seitendorf | German Empire | Löwenberg i. Schles. | 1939 |
| Ustronie | Under Polish administration | Lwówek Śląski | 1945 |
| Ustronie | Poland | Jelenia Góra | 1992 |