What is "nadruvians"

The Nadruvians were one of the now-extinct Prussian clans. They lived in Nadruvia (alternative spellings include: Nadruva, Nadrowite, Nadrovia, Nadrauen, Nadravia, Nadrow and Nadra), a large territory in northernmost Prussia. They bordered the Skalvians on the Neman River just to the north, the Sudovians to the east, and other Prussian tribes to the south and west. Most information about the clan is provided in a chronicle by Peter von Dusburg.