Seth was formerly part of the German Empire. In the German Empire, the place was called Seth.
The place is now called Sæd (Tønder-Sæd) and belongs to Denmark.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Seth | German Empire | Tondern | before the Versailles Treaty |
| Sæd | Denmark | Tønder | after the Versailles Treaty |
| Sæd (Tønder-Sæd) | Denmark | Sønderjylland | 1993 |