Gmajna was formerly part of the German Empire. In the German Empire, the place was called Rieg.
The place is now called Gmajna and belongs to Slovenia.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Gmajna | Austro-Hungary | Gurkfeld/Krško | before the Treaty of Saint-Germain |
| Gmajna | Yugoslavia | Krško | after the Treaty of Saint-Germain |
| Rieg | German Empire | Rann | 1941 |
| Gmajna | Yugoslavia | Trbovlje | 1945 |
| Gmajna | Yugoslavia | Socialistična rep. Slovenija | 1992 |
| Gmajna | Slovenia | Slowenien | 1991 |