Abstrakt: In this sketch the author refers to the work published ten years ago, entitled A History of East Central Europe (vol. 1-2, ed. by J. Kłoczowski, Lublin 2000) and undertakes a polemics with the book from the perspective of a researcher of the history of Lithuania and the Grand Duchy of Lithuania. The basic drawback of the synthesis is the lack of consideration for Lithuanian historiography in such fundamental problems as: creating the national Lithuanian identity among people of Baltic origin and the awareness of belonging to the Grand Duchy as a common state among the population of Ruthenian origin. Therefore, relying on older historiography leads to erroneous conclusions, particularly as for the genesis of the effects of the Union of Lublin, as seen only from the Polish perspective. However, as the author notices, the research effort of a new generation of both Lithuanian and Polish historians results in new interpretations of the mutual past, taking into consideration all its aspects.