You can also specify that the results returned are from a specific country-level domain, by adding site:de 


DuckDuckGo Community Manager
posted by zac Staff5 years and 11 months ago Link

That neither region, nor site:de helps in getting German *language* results. You'll get "Germany" results.

It would be useful to have a region setting similar to Latin America (xl-es) for German speaking countries, (e.g. xl-de := de-de OR at-de OR ch-de).
posted by <hidden> • 2 years and 1 month ago Link
kl=de-de should work for you, example:
posted by x.15a2 Community Leader2 years and 1 month ago Link