They are descended from Masovians (; ), who were Polish settlers from Mazovia. These settlers moved to the Duchy of Prussia during and after the Protestant Reformation. They spoke the Masurian dialect. Since the middle 19th century, High German was increasingly used among Masurians as opposed to Low German used by most of East Prussia's German population. Many Masurians were often bilingual in German and Polish languages. In the 19th century, the Masuria region of East Prussia was named after the Masurians.