Poland tried to invade the territory of the Germanic- slavic tribe of the Prussians, but they were not able to cope with them. So Duke Conrad of Masowien asked the German Order for help. Therefore they should get the reign over Prussia. They accepted and pacified and christianized the Prussians. This was about 1200. After ruling over 250 years relative peacefully, where many settlers came from Germany and many settlements were founded or enlarged, Marienburg, Danzig, Königsberg, Thorn for example, while Danzig and Königsberg became members of the Hanse and Danzig had the law of Lübeck, Poland and Lithunia became united. This was against the German order. They had to fight for their land, but lost the decisive battle of Tanneberg in 1454. Prussia became a Polish vassal and was divided. While East Prussia became the duchess of Prussia, later belonging to Brandenburg, West Prussia was anected by Poland. They tried to polonize this territory but at least in the towns like Danzig they were unsuccessfull. In the last decades of the 17th century after the 30 years war the Grand Elector could get independence from Poland. But only East Prussia was under the ruling of Brandenburg. In 1701 Prussia beacme a kingdom, But Frederic I. became only king IN Prussia. West Prussia became not part of Prussia until the the first Polish Division. Finally Prussia was reunited. Until 1919 when Poland got most parts of west Prussia and of course 1945, when Germany lost all of the areas east of the Oder- Neiße line. So originally East Prussia was never part of Poland ,while west Prussia was ruled by Poland, but inhabitated by (mostly) German.
Adler
