Patriarch of Aquileia in the context of Patriarchate of Aquileia

The Patria del Friuli (Latin: Patria Fori Iulii, Friulian: Patrie dal Friûl), also known as the Patriarchal State of Aquileia (Italian: Stato patriarcale di Aquileia), was the territory under the temporal (political) rule of the Patriarch of Aquileia, and one of the ecclesiastical states within the Holy Roman Empire. It was created in the second half of the 11th century, and existed up to the first half of the 15th century. As in the case of other ecclesiastical states, its territory was not identical with jurisdictional borders of the Patriarchate of Aquileia. In 1420, the Republic of Venice acquired and consequently annexed the territory, thus depriving the Patriarch of Aquileia of his temporal powers. Under Venetian rule, the region continued to be administered for some time under its own laws and customs.

In the history of Christianity and later of the Roman Catholic Church, there have been several Councils of Aquileia. The Roman city of Aquileia at the head of the Adriatic Sea is the seat of an ancient episcopal see, seat of the Patriarch of Aquileia.

Latin Patriarch may refer to these Catholic sees and/or titles :

• Latin Patriarch of Constantinople (suppressed)
• Latin Patriarch of Antioch (suppressed)
• Latin Patriarch of Alexandria (suppressed)
• Latin Patriarch of Jerusalem
• Latin Patriarch of Ethiopia (suppressed)

• Patriarch of Venice
• Patriarch of Lisbon
• Patriarch of the East Indies (vested in Goa)
• Patriarch of Aquileia (extinct)
• Patriarch of Grado (merged with the office of the Bishop of Castello to become the Patriarch of Venice)
• Patriarch of the West Indies (extinct)

Patriarch of Rome and all the West and Patriarch of the West are two rarely mentioned titles of the Pope. Catholicism also recognizes the patriarchs of the East, but they would never be called "Latin."

The Duchy of Tridentum (Trent) was an autonomous Lombard duchy, established by Euin during the Lombard interregnum of 574–584 that followed the assassination of the Lombard leader Alboin. The stronghold of Euin's territory was the Roman city of Tridentum in the upper valley of the Adige, in the foothills of the Alps in northern Italy, where the duchy formed one of the marches of the Lombard Kingdom of Italy. There he shared power with the bishop, who was nominally subject to the Patriarch of Aquileia. In 574–75, Lombard raiding parties pillaged the valley of the Rhône, incurring retaliatory raids into the duchy by Austrasian Franks, who had seized control of the mountain passes leading into the kingdom of Burgundy. Euin was at the head of the army loyal to Authari that went into the territory of the duke of Friuli in Istria, c 589, and he was sent by Agilulf to make peace with the Franks his neighbors, in 591. After Euin's death c 595, Agilulf installed Gaidoald, who was a Catholic, rather than an Arian Christian. After some friction between king and duke, they were reconciled in 600. The separate Lombard duchy of Brescia was united with Tridentum in the person of Alagis, a fervent Arian and opponent of the Lombard king, Perctarit, who was killed in the battle of Cornate d'Adda (688).

With the collapse of the Lombard kingdom in 773–74, the duchy of Tridentum passed into Frankish control and was transformed. After German king Otto I had subdued the Italian kingdom in 952 he incorporated Tridentum into the March of Verona. Its strategic position controlling the Alpine mountain passes encouraged the eleventh-century Holy Roman Emperors to invest the Bishop Ulrich II of Trent with temporal powers over a sizable territory, as an independent prince of the Empire, with the powers and privileges of a duke. A succession of Prince-Bishops ruled, except for a few short intervals, until 1802, when the bishopric was secularized and became a part of Austrian Tyrol.