Obersteiermark (Upper Styria), the high mountain region of north-western Styria; includes the Upper Mur Valley (between Predlitz and the narrows at Mixnitz) with the Mürz Valley, the Upper Enns Valley (between Mandling pass and Altenmarkt) with the Salza Valley and the Styrian part of the Salzkammergut region, the Niedere Tauern mountains and the Limestone Alps of Styria and Lower Austria. Separated from the remaining part of the province of Styria by the Styrian Rim mountains (Stubalpe, Gleinalpe and Hochalpe alpine mountains as well as the Fischbach Alps). Administrative division into the political districts of Mürzzuschlag, Bruck an der Mur, Leoben, Knittelfeld, Judenburg, Murau and Liezen, principal town Leoben (diocese from 1786-1859). With an area of 9,585 km2 Upper Styria constitutes 58.5 % of the area of Styria, but is home to only 32 % (pop. 379,155) of the entire Styrian population, most of who live in the mining and industrial region of the Mur-Mürz-Furche.