Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Sadkowo is a village in the administrative district of Gmina Dzierz nia, within P o sk County, Masovian Voivodeship, in east-central Poland. The establishment of a Polish state is often identified with the adoption of Christianity by its ruler Mieszko I, in 966, when the state covered territory similar to that of present-day Poland. The Kingdom of Poland was formed in 1025, and in 1569 it cemented a long association with the Grand Duchy of Lithuania by signing the Union of Lublin, forming the Polish Lithuanian Commonwealth.