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The Czortoryski princely family representatives held high government positions first in the Grand Duchy of Lithuania and then in the Polish-Lithuanian Commonwealth. The cultural heritage of the family is extremely extensive: from written documents to architectural monuments on the territory of the modern states: Poland, Ukraine, Lithuania and Belarus. The subject of the article is the history of the Czortoryski princes family archive formation during the 15–16th centuries. Having started since the 40s of the 16th century, the number of written documents increased significantly, so we limited the upper chronological limit with 1524, the death year of Semen Oleksandrovych Czortoryski, the representative of the Lithuanian branch. The origin of the family is connected with the name of Prince Kostiantyn, the son of Grand Duke of Lithuania Olgerd or his brother Koriat. His own documentary heritage is not known to us. His descendants, namely Vasyl Kostiantynovych and his sons Ivan, Olexandr and Mykhailo are of great importance for the study of the subject matter in this research. Among the documentary materials studied, we note the first grants of the Grand Duke of Lithuania Kazimierz Jagiellonczyk to Prince Ivan Vasylovych, which are known from later confirmations. This prince left no descendants, and thus it is unlikely that his personal archive has survived. Two other Vasyl Kostiantynovich's sons Olexandr and Mykhailo founded two branches of the family: Lithuanian (Lohoisk/Lohozsk) and Volyn. According to the information from the sources we have found, we can assume that, firstly the family archive dates back to the 40s of the 15th century, when the first source information was recorded, and secondly each family branch kept its family documents separately. Accordingly, two collections were formed: 1) descendants of Oleksandr Vasylovych; 2) descendants of Mykhailo Vasylovych.
Dmytro Vashchuk (Mon,) studied this question.