In 1236
Peter of Dusburg wrote that Nadruvia was the location of
Romuva, the sacred center of
Baltic religion. From Romuva Kriwe, the chief priest or "pagan Pope", ruled over the religion of all the Balts. No other sources mention the place. Scientists have considerable doubts if such an organized structure existed. As the northernmost clan, Nadruvians were conquered last by the
Teutonic Knights, a German crusading military order. In 1230 the Knights set up their base in the
Chełmno Land in Poland and proceeded to conquer all pagans and convert them to Christianity. The first military encounters between Nadruvians and the Knights began ca. 1255 when the Knights were trying to conquer
Sambians, western neighbors of Nadruvians. Dusburg alleges that Nadruvians had several fortresses with strong garrisons. Two distorted names are given (
Otholicia and
Cameniswika) and it is very difficult to identify their location. Nadruvians built another castle at
Velowe when the Knights reached their lands. Sambians had to surrender in 1277, but the conquest of Nadruvians was delayed by the
Great Prussian Uprising that broke out in 1260. The uprising ended in 1274, and Nadruvians fell in 1275. Prussian fortress at Velowe was captured by the Teutonic Knights and renamed to
Wehlau. A handful of Nadruvians retreated into
Grand Duchy of Lithuania. After the subsequent
Thirteen Years' War, the longest of all Polish–Teutonic wars, since 1466, it formed part of Poland as a
fief held by the Teutonic Order, and after 1525 held by secular
Ducal Prussia. Eventually, sometime after the 16th century, Nadruvians became extinct. The bulk of Nadruvia became part of the predominantly Lithuanian-inhabited region of
Lithuania Minor. ==Etymology and classification==