The Styrian lands had already been ruled in personal union by the Babenberg dukes of Austria since 1192 and were finally seized with the Austrian lands by the Habsburg king Rudolph I of Germany upon his victory in the 1278 Battle on the Marchfeld. In 1335 Rudolph's grandson Duke Albert II of Austria also received the Carinthian duchy with the adjacent March of Carniola at the hands of Emperor Louis the Bavarian as Imperial fiefs. When in 1365 Albert's son Duke Rudolf IV of Austria suddenly died at the age of 26, Emperor Charles IV enfeoffed his younger brothers Albert III with the Pigtail and Leopold III the Just, who however began to quarrell about the Habsburg heritage. By the 1379 Treaty of Neuberg they finally split late Rudolf's territories: The elder Albertinian line would rule in the Archduchy of Austria proper, while the younger Leopoldian line ruled the Styrian, Carinthian and Carniolan duchies, then subsumed under the denotation of "Inner Austria". At that time their share also comprised Tyrol and the original Habsburg possessions in Swabia, called Further Austria; both collectively referred to as "Upper Austria" in that context, also not to be confused with the modern state of that name. When Leopold III was killed in the 1386 Battle of Sempach against the Old Swiss Confederacy, the Leopoldian heritage fell to his eldest son Duke William the Courteous, who upon the death of his uncle Albert III in 1395 also raised claims to the Archduchy of Austria against Albert's only son and heir Duke Albert IV. Both sides came to an agreement to maintain the Neuberg division but also to assert the common rule over the Habsburg lands. Therefore, from 1404 William acted as Austrian regent for his minor nephew Albert V. The Tyrolean and Further Austrian lands passed to William's younger brother Duke Leopold IV the Fat. When Duke William died without issue in 1406, the Leopoldian line was further split among his younger brothers: while Leopold IV assumed the regency in Austria, the Inner Austrian territories passed to Ernest the Iron, while the Tyrolean/Further Austrian passed to the youngest brother Frederick of the Empty Pockets. In 1457 the Leopoldian line again could assume the rule over the Austrian archduchy, when Ernest's son Duke Frederick V of Inner Austria succeeded his Albertine cousin Ladislaus the Posthumous who had died without issue. 1490 saw the reunification of all Habsburg lines, when Archduke Sigismund of Further Austria and Tyrol resigned in favour of Frederick's son Maximilian I. In 1512, the Habsburg territories were incorporated into the Imperial Austrian Circle. The dynasty however was split up again in 1564 among the children of deceased Emperor Ferdinand I of Habsburg. Under the Inner Austrian line founded by his younger son Archduke Charles II, the lands became a centre of the Counter-Reformation, carried out by the Jesuits with great determination. The cadet branch prevailed again, when Charles' son and successor as regent of Inner Austria, Archduke Ferdinand II, was crowned King of Bohemia in 1617, King of Hungary in 1618, and finally succeeded his cousin Matthias in the Archduchy of Austria and as Holy Roman Emperor in 1619. His intentions to translate the absolutist and anti-reformationist Inner Austrian policies to the Crown of Bohemia sparked the Thirty Years' War. The Further Austrian/Tyrolean line of Ferdinand's younger brother Archduke Leopold V survived until the death of his son Sigismund Francis in 1665, whereafter all territories ultimately returned to common control with the other Austrian Habsburg lands. The political administration of Inner Austria was centralized at Graz in 1763. Inner Austrian stadtholders went on to rule until the days of Empress Maria Theresa in the 18th century.
