Časlau was formerly part of the German Empire. In the German Empire, the place was called Čáslav.
The place is now called Čáslav and belongs to Czechoslovakia.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Časlau | Austro-Hungary | Časlau | before the Treaty of Saint-Germain |
| Čáslav | Austro-Hungary | Časlau | before the Treaty of Saint-Germain |
| Čáslav | Czechoslovakia | Čáslav | after the Treaty of Saint-Germain |
| Tschaslau | German Empire | Tschaslau | 1939 |
| Čáslav | German Empire | Tschaslau | 1939 |
| Čáslav | Czechoslovakia | Čáslav | 1945 |
| Čáslav | Czechoslovakia | Střední Čechy | 1992 |