In 1257 Albrecht of Sax-Misox sold Wartenstein Castle and the villages of Pfäfers, Valens, Vättis and Untervaz to Pfäfers Abbey for 300 silver marks. After the decline of the imperial Hohenstaufen family the Sax-Misox lost the Blenio Valley, Monte Dongo and Clanx Castle. Their lands were reduced to the Core of the Misox Valley with the San Bernardino Pass and the Walser settlements in the Rheinwald Valley. The distant estate at Arth was granted as a fief to Heinrich and Albrecht von Grünenfels in 1295.