The Treaty of Neuberg, concluded between the Austrian duke Albert III and his brother Leopold III on 25 September 1379, determined the division of the Habsburg hereditary lands into an Albertinian and Leopoldian line.
Albert and Leopold were the younger brothers of Duke Rudolf IV of Austria, who upon the death of his father Duke Albert II in 1358 had assumed the rule not only over the Austrian duchy, but also over the Duchy of Styria, ruled in personal union with Austria according to the 1186 Georgenberg Pact, and over the Duchy of Carinthia with the adjacent March of Carniola.
Rudolf, an energetic monarch struggling with the rivalling Wittelsbach and Luxembourg dynasties, immediately elevated himself to an Austrian archduke by the Privilegium Maius. In 1363 he acquired the County of Tyrol from the last Meinhardiner countess Margraret and the next year added "Duke of Carniola" to his titles. Upon his early death in 1365, his brothers inherited a significant cluster of Imperial States stretching from the Habsburg residence Vienna to the dynasty's original Further Austrian possessions in the west, the nucleus of the Habsburg Monarchy.