Members of the House of Ortenburg were the most prominent landowners in the area from the 11th century onwards. They were at their apex in the 13th century in terms of land, encompassing almost all of the Sava Valley from its source to its confluence with the Sora River. The House of Ortenburg promoted colonization of the Upper Sava Valley, especially in ore-rich areas. Throughout the 14th, 15th, and 16th centuries, small settlements of Plavž, Sava, Murova, and Slovenski Javornik were founded. By decree of King Alexander I of Yugoslavia, all of these settlements were amalgamated into the town of Jesenice on March 20, 1929.