Kohlby was formerly part of the German Empire. In the German Empire, the place was called Kohlby.
The place is now called Koldby and belongs to Denmark.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Kohlby | German Empire | Tondern | before the Versailles Treaty |
| Koldby | Denmark | Tønder | after the Versailles Treaty |
| Koldby | Denmark | Sønderjylland | 1992 |