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Inner Austria (German: Innerösterreich, Slovene: Notranja Avstrija, Italian: Austria Interna) was a term used from the late 14th to the early 17th century for the Habsburg hereditary lands south of the Semmering Pass, referring to the Imperial duchies of Styria, Carinthia, Carniola and the Austrian Littoral. The residence of the Inner Austrian dukes was at Graz.
The Inner Austrian territory stretched from the northern border with the Archduchy of Austria on the Alpine divide over Upper and Lower Styria down to Carniola, where the Lower and White Carniolan lands (the former Windic March) bordered on the Habsburg Kingdom of Croatia. In the west, the Carinthian lands stretched to the Archbishopric of Salzburg and the Habsburg County of Tyrol, while in the east, the Mur River formed the border with the Kingdom of Hungary.
In the south, the County of Görz, which had passed to the House of Habsburg in 1500, and Duino (Tybein) bordered on the Domini di Terraferma of Venice. The Imperial Free City of Trieste on the Adriatic Coast linked to assorted smaller possessions in the March of Istria around Pazin and the free port of Rijeka (later corpus separatum of Fiume) in Liburnia.
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 Albert's son Duke Rudolf IV of Austria in 1365, his younger brothers Albert III and Leopold III quarelled about his heritage and in the Treaty of Neuberg of 1379 finally split the Habsburg territories: The Albertinian line would rule in the Archduchy of Austria proper (then sometimes referred to as "Lower Austria" (Niederösterreich), but comprising modern Lower Austria and most of Upper Austria), while the Leopoldian line ruled in the Styrian, Carinthian and Carniolan territories, 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; sometimes both were collectively referred to as "Upper Austria" (Oberösterreich) in that context, also not to be confused with the modern state of that name.
After the death of Leopold's eldest son William in 1406, the Leopoldinian line was further split among his brothers into the Inner Austrian territory under Ernest the Iron and a Tyrolean/Further Austrian line under Frederick IV. In 1457 Ernest's son Duke Frederick V of Inner Austria also gained the Austrian archduchy after his Albertine cousin Ladislaus the Posthumous 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. The Inner Austrian line founded by Archduke Charles II prevailed again, when his son and successor as regent of Inner Austria Ferdinand II in 1619 became Archduke of Austria and Holy Roman Emperor as well as King of Bohemia and Hungary in 1620. The Further Austrian/Tyrolean line of Ferdinand's brother Archduke Leopold V survived until the death of his son Sigismund Francis in 1665, whereafter their territories ultimately returned to common control with the other Austrian Habsburg lands. Inner Austrian stadtholders went on to rule until the days of Empress Maria Theresa in the 18th century.
Rulers of Inner Austria 
Leopoldinian line 
- Leopold III (1379-1386)
- William, son (1386-1406)
- Ernest the Iron, brother (1406-1424)
- Frederick V, son (1424-1457), also King of the Romans (as Frederick IV) from 1440 and Holy Roman Emperor (as Frederick III) from 1452, jointly with his brother
- Albert VI (1424-1463)
became Archduke of Austria in 1457, Habsburg territories united in 1490
Inner Austrian line 
- Charles II (1564-1590)
- Ferdinand II, son (1590-1619), also King of the Romans from 1618 and Holy Roman Emperor from 1619
became Archduke of Austria in 1619. All Habsburg territories again united in 1655.