After World War II, the Polish state borders were shifted to the west. Historically, the lands annexed by Poland, known as the Recovered Territories, have belonged to various states over the centuries. For this reason, the right of Polish people to these lands, as well as the “Polishness” of the territory, was called into question. The authorities of the People’s Republic carried out a large-scale propaganda campaign intended to prove their rights to these lands. Historians from various academic institutions joined in the campaign. Polish historiography of the first decade of the People’s Republic is frequently accused of being biased and “subservient” to the new government. The main objective of this article is to overthrow this stereotype. The author presents the history of scientific institutions concerning themselves with the problem of the Recovered Territories, profiles of prominent historians and the results of their research work on the history of Upper and Lower Silesia and Western Pomerania.