In the Treaty of Neuberg, concluded between the Habsburg Dukes Albert III and Leopold III on September 9, 1379 in Neuberg an der Mürz , the Habsburg lands were divided between the two brothers. While Albert retained the Duchy of Austria, Leopold became the exclusive ruler of Styria (including Wiener Neustadt), Carinthia, Carniola, the Windish March , Gorizia, the Habsburgs' posessions in Friuli, Tyrol and Further Austria.

With the treaty began a split between the Albertinian and Leopoldinian lines of the Habsburg families and the Austrian lands which was to end only in 1490.