The German Wikipedia article is pretty clear on this.
Name | Erscheinungsjahr | Spielplan
| (Publication Year) | (Board Map)
--------------------------------------------------------
Zug um Zug | 2004 | USA
Zug um Zug Europa | 2005 | Europa (Europe)
The first version to be released in Germany was the US board in 2004. This went on to win the prestigeous Spiel des Jahres (Game of the Year) award in the year 2004; awarded by a jury of critics.
A game is only eligible to win Spiel des Jahres in the year it was published in (unless it was published in the previous year after the list of nominees had been closed). And there has not been the case of a spin-off version winning Spiel des Jahres if the main one did not. In fact, while I don’t have sources it is very unlikely for spin-offs even to be considered, since they typically follow the same principle as the main game which would have been eligible earlier.
The Europe board was not released until the following year, 2005. The table at the bottom of the Wikipedia article indicates that.
Incidentally, the game did receive a minor rebranding in Germany by getting a new (German) name: Zug um Zug. In Scandinavia (specifically Finland, where I bought the Scandinavia version), the original name was kept.