Duchy of Silesia
In 1173 Bolesław returned and he agreed to let Mieszko and Bolesław rule in their own Duchies, separated from the Duchy of Silesia. This led to the creation of the Duchy of Racibórz for Mieszko I and the Duchy of Opole for Jarosław, beginning the fragmentation of the Duchy of Silesia. The territories controlled by Mieszko I and Jarosław roughly corresponded to what is known as Upper Silesia, while the territories remaining with Bolesław I roughly corresponded to Lower Silesia.