In the year 600 AD, the land of Salzburg was ruled by Bavarian Dukes. In the year 700 they appointed Bishop Rupert von Worms for missionary purposes to the region. He chose the monastery of St. Peter in Juvavum (Salzburg) as the base for his missionary projects. Thanks to the extensive donations made by the Bavarian dukes Salzburg became one of the richest churches in Franconia. In 739, Salzburg was raised to a bishopric, then, in 798, to an archdiocese. This era also saw the construction of Salzburg Cathedral, consecrated in 774 by Bishop Virgil, who came from Ireland.

In the cultural and political sphere the first centuries of Salzburg’s mediaeval history proved to be very significant, as missionary activity resulted in an extension of its area of influence into the territories of present-day Croatia and Hungary. However, the Hungarian invasions at the beginning of the tenth century halted the first stage of proselytisation and colonisation towards the East. Considering the property of large manorial lands as a basis for power, from the beginning of the 13th century the archbishops increasingly ousted the large earldom families and expanded their own area of influence. One can speak of Land Salzburg from 1292 as it had its own “Law of the Land” and Eberhard II, probably the most eminent archbishop of this period, had already adopted the title of prince in 1213. Towards the end of the Middle Ages, the Land and archbishopric of Salzburg comprised what is nowadays the federal Land, the territories west of the Saalach and the Salzach that remained in Bavaria in 1816, as well as regions in present-day Tyrol and East Tyrol. Furthermore, the Land also owned properties in what is now known as Lower Austria, Upper Austria, Styria and Carinthia, as well as in Slovenia and Croatia. Until the end of the independent archdiocese in 1803, the entire territory encompassed 14,000 square kilometres, which is almost twice as much as the area of the present-day federal land and the population numbered about 150,000 inhabitants. From earliest times Salzburg has always been divided into two regions, on both sides of the Tauern mountains. South of the Tauern was the Lungau region, whereas areas north of the Tauern mountains are split into alpine foreland and mountainous regions. The names "Pongau” and “Pinzgau” date back to the 8th century, “Lungau” was first mentioned in documents in 923. The “Tennengau” received its name during the second half of the 19th century but the name “Flachgau” is a word creation of the 20th century.