It comprised the secular territory ruled by the archbishops of Salzburg, as distinguished from the much larger Catholic diocese founded in 739 by Saint Boniface in the German stem duchy of Bavaria.

Members of the Bavarian Circle from 1500, the prince-archbishops bore the title of Primas Germaniae, though they never obtained electoral dignity; actually of the six German prince-archbishoprics (with Mainz, Cologne and Trier), Magdeburg, Bremen and Salzburg received nothing from the Golden Bull of 1356.

The former archepiscopal lands are traditionally subdivided into five historic parts (Gaue): Flachgau with the Salzburg capital and Tarus Tennengau around Hallein are both located in the broad Salzach valley at the rim of the Northern Limestone Alps; the mountainous (Innergebirg) southern divisions are Pinzgau, Pongau around Bischofshofen, and southeastern Lungau beyond the Radstädter Tauern Pass.

In the north and east, the prince-archbishopric bordered on the Duchy of Austria, a former Bavarian margraviate, which had become independent in 1156 and, raised to an archduchy in 1457, developed as the nucleus of the Habsburg monarchy.

The Vita Sancti Severini biography by the Early Christian chronicler Eugippius, reported that during the Decline of the Roman Empire about 450 AD the local capital Iuvavum in the Noricum ripense province was already home to two churches and a monastery.

A disciple of Saint Severinus, he was martyred in the retreat from Noricum, after the Germanic Western Roman officer Odoacer had deposed the last Emperor Romulus Augustulus and declared himself King of Italy in 476.

About 696 Saint Rupert, then Bishop of Worms in Frankish Austrasia and later called the apostle of Bavaria and Carinthia, came to the region from the Bavarian town Regensburg and laid the foundations for the re-establishment of the Salzburg diocese.

After erecting a church at nearby Seekirchen he discovered the ruins of Iuvavum overgrown with brambles and remnants of the Romance population, who had maintained Christian traditions.

St Peter's Abbey received large estates in the Flachgau (Rupertiwinkel) and Tennengau regions from the hands of Duke Theodon II, including several brine wells and salt evaporation ponds which earned Iuvavum its German name Salzburg.

In 739 Archbishop Boniface, with the blessing of Pope Gregory III, completed the work of Saint Rupert and raised Salzburg to a bishopric, placed under the primatial see of the Archdiocese of Mainz.

Arno, bishop since 785, enjoyed the respect of the Frankish king Charlemagne who assigned to him the missionary territory between the rivers Danube in the north, the Rába (Raab) in the east and the Drava in the south, an area which had recently been conquered from the Avars.

While Arno was in Rome attending to some of Charlemagne's business in 798, Pope Leo III appointed him Archbishop over the other bishops in Bavaria (Freising, Passau, Regensburg, and Säben).

Archbishop Adalwin (859–873) suffered great troubles when King Rastislav of Moravia attempted to remove his realm from the ecclesiastical influence of East Francia.

In 870 Pope Adrian II appointed the "Apostle of the Slavs" St. Methodius the Archbishop of Pannonia and Moravia at Sirmium, entrusting him large territories under the overlordship of the Salzburg diocese.

He then attempted to keep the populace Catholic, and during the Latin War was besieged in the Hohen-Salzburg, declared a "monster" by Martin Luther, and two later uprisings by the peasants lead to suffering to the entire archdiocese.

[clarification needed] Archbishop Wolf Dietrich von Raitenau gave the Protestants the choice of converting to Catholicism or leaving Salzburg.

The powers of this title – non-jurisdictional – are limited to being the Pope's first correspondent in the German-speaking world, but had once included the right to preside over the Princes of the Holy Roman Empire.