Masuria (Polish: Mazury; German: Masuren (help·info)) is an area in northeastern Poland famous today for its 2000 lakes.
In the 11th-13th century, the territory was inhabited by the Old Prussians, also called Baltic Prussians, an Baltic ethnic group that inhabited Prussia, the lands of the southeastern coastal region of the Baltic Sea, in the area around the Vistula and Curonian Lagoons. They spoke a language now known as Old Prussian and followed a religion believed by modern scholars to be closely related to Lithuanian paganism. Although they bore the name of a 19th century German political entity, they were not "Germans." They were converted to Catholicism in the late-13th and 14th centuries, after conquest by the Knights of the Teutonic Order, and then to Protestantism in the early 16th century. In the 15th-19th centuries, the territory was part of the Duchy of Prussia, the Kingdom of Prussia and eventually the German Empire. After the Unification of Germany in 1871, the policy of Germanization sought to eradicate linguistic roots of the Old Prussian and the Polish languages. As a result of the East Prussian plebiscite after World War I Masuria remained within Weimar Germany. After World War II the area became Polish, the local populace was expelled or subsequently left the area.
Today, the region's economy relies largely on eco-tourism and agriculture. The 2,000 lakes for which the region is famous offer varieties of water sports, and vacation activities.