The Silesian Piasts were the eldest line of the Piast dynasty beginning with Władysław II the Exile, son of Bolesław III Wrymouth, Duke of Poland. According to Bolesław's testament Władysław II the Exile was granted the Silesian province as his hereditary realm and also the Seniorate Province because he was the oldest among the Piasts.
Read more about Silesian Piasts: Early History, Struggle For The Polish Crown, Fragmentation and Turn To Bohemia, Vassals of Bohemia and Decline, Silesian Piasts and Poland