 The varied history with changing aristocratic possessions resulted in an abundance of castles, especially in the Jelenia Góra valley.The first known states to hold power in Silesia were probably those of Greater Moravia at the end of the 9th century and Bohemia early in the 10th century.In the 10th century, Silesia was incorporated into the early Polish state, and after its division in the 12th century became a Piast duchy.