Mieszko's small share was enlarged the first time in 1177, when he received the territories of Bytom, Oświęcim, Zator, Pszczyna and Siewierz from his uncle High Duke Casimir II the Just of Poland.
Mieszkos ret beskedne område voksede første gang i 1177, da han modtog områderne Bytom, Oświęcim, Zator, Pszczyna og Siewierz af sin onkel Kasimir 2. af Polen.