Herzogtum Oppeln
Defying the Polish agnatic seniority principle, Mieszko Tanglefoot in 1202 occupied the neighbouring Duchy of Opole from his nephew Henry the Bearded, forming the united Upper Silesian Duchy of Opole and Racibórz. His descendants ruled Upper Silesia until the death of Mieszko's grandson Duke Władysław Opolski in 1281, whereafter Opole-Racibórz was again divided among his four sons. The eldest, Mieszko, initially ruled the Duchy of Racibórz with Cieszyn and Oświęcim, jointly with his minor brother Przemysław. After another partition in 1290, Mieszko took his residence in Cieszyn and became the first Duke of Teschen.