Annexation to Poland of the so-called The Recovered Territories in 1945 was an impulse for creating new tasks for Polish historical sciences. And the history of the Polish state was so arranged that the Middle Ages had the greatest potential for searching for national traditions. Polish scientists, who took steps to create scientific, museum and conservation structures in these areas, also began researching the past of these lands. For many of them this was unknown territory, they had almost no publications on this subject. They had to face the results of earlier German work, developing a new Polish narrative about the past. A similarly pioneering stage took place in the work on securing monuments and remnants of the cultural heritage of these areas. The community of archaeologists, historians, art historians and conservators was not numerous in pre-war Poland, and many died during the war.