By the 11th century, the Germanization of what is now Lower Austria, effectively isolated the Slovene-inhabited territory from the other western Slavs, speeding up the development of the Slavs of Carantania and of Carniola into an independent Carantanian/Carniolans/Slovene ethnic group. By the late Middle Ages, the historic provinces of Carniola, Styria, Carinthia, Gorizia, Trieste, and Istria developed from the border regions and were incorporated into the medieval German state. The consolidation and formation of these historical lands took place in a long period between the 11th and 14th centuries, and were led by a number of important feudal families, such as the Dukes of Spanheim, the Counts of Gorizia, the Counts of Celje, and, finally, the House of Habsburg. In a parallel process, an intensive German colonization significantly diminished the extent of Slovene-speaking areas. By the 15th century, the Slovene ethnic territory was reduced to its present size.