Trojan was formerly part of the German Empire. In the German Empire, the place was called Trojany.
The place is now called Trojany and belongs to Czech Republic.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Trojan | Austro-Hungary | Kralowitz | before the Treaty of Saint-Germain |
| Trojany | Austro-Hungary | Kralowitz | before the Treaty of Saint-Germain |
| Trojany | Czechoslovakia | Kralovice | after the Treaty of Saint-Germain |
| Trojan | German Empire | Kralowitz | 1939 |
| Trojany | German Empire | Kralowitz | 1939 |
| Trojany | Czechoslovakia | Plasy | 1945 |
| Trojany | Czechoslovakia | Plzeň-sever | 1992 |
| Trojany | Czech Republic | Plzeň-sever | 1993 |