What is "pomesanians"

Pomesanians were one of the Prussian clans. They lived in Pomesania , a historical region in modern northern Poland, located between the Nogat and Vistula Rivers to the west and the Elbląg River to the east. It is located around the modern towns of Elbląg and Malbork. As the westernmost clan, the Pomesanians were the first of the Prussians to be conquered by the Teutonic Knights, a German military crusading order brought to the Chełmno Land to convert the pagans to Christianity. Due to Germanization and assimilation, Pomesanians became extinct some time in the 17th century.