Ploscha was formerly part of the German Empire. In the German Empire, the place was called Ploscha.
The place is now called Blažim and belongs to Czech Republic.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Ploscha | Austro-Hungary | Saaz | before the Treaty of Saint-Germain |
| Blažim | Austro-Hungary | Saaz | before the Treaty of Saint-Germain |
| Blažim | Czechoslovakia | Žatec | after the Treaty of Saint-Germain |
| Ploscha | Czechoslovakia | Žatec | after the Treaty of Saint-Germain |
| Ploscha | German Empire | Saaz | 1938 |
| Blažim | Czechoslovakia | Žatec | 1945 |
| Blažim | Czechoslovakia | Louny | 1992 |
| Blažim | Czech Republic | Louny | 1993 |