Koslau was formerly part of the German Empire. In the German Empire, the place was called Koslau.
The place is now abandoned and the area belongs to Czech Republic.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Koslau | Austro-Hungary | Kaaden | before the Treaty of Saint-Germain |
| Kozlov | Austro-Hungary | Kaaden | before the Treaty of Saint-Germain |
| Kozlov | Czechoslovakia | Kadaň | after the Treaty of Saint-Germain |
| Koslau | Czechoslovakia | Kadaň | after the Treaty of Saint-Germain |
| Koslau | German Empire | Kaaden | 1938 |
| Kozlov | Czechoslovakia | Kadaň | 1945 |
| - aufgelassen - | Czechoslovakia | Karlovy Vary | 1992 |
| - aufgelassen - | Czech Republic | Karlovy Vary | 1993 |