Between the 14th and 17th centuries, settlers from northern Mazovia moved to former territories of Old Prussians, following conquests by the Teutonic Order, and the erection of the Monastic state of the Teutonic Knights.
The bishopric of Warmia became in 1466 an autonomous part of Royal Prussia, and remained part of Polish–Lithuanian Commonwealth until 1772 (see: Partitions of Poland). While Mazurs in the neighboring Ducal Prussia became Protestants when that Duchy adopted Lutheranism in the 16th century, most Warmiaks, populating the areas around Olsztyn, remained Catholics.
During World War II, the Warmiaks were persecuted by the Nazi Germany government, which wanted to erase all aspects of Polish culture and Polish language in Warmia. After the war, due to their Polish roots, they were not victims of Expulsion of Germans after World War II, but in the course of the time, large numbers of Warmiaks decided to leave their native land and settle in more prosperous West Germany.