The states were created to favor passage to Imperial armies across the Alps towards Italy along the two ancient roads, the Via Claudia-Augusta and the Via Altinate, entrusting the area to two bishops instead of often rebellious lay princes.

The princes of Trento maintained a strong allegiance to the Emperor, even when the latter was excommunicated: this because they need his protection against the growing power of subjects like the counts of Tyrol, who controlled the area around Bozen, those of Eppan, and others.

Allied with the Bishop of Brixen and allowing wide estates to the Teutonic Knights he managed to thwart at all the nobles' strength, and recovered much of the territories lost in the past years.

In 1236 Emperor Frederick II of Hohenstaufen deposed the bishops and ensured to himself the authority over the important military area of Trento, annexing it to the Mark of Treviso — the administration was entrusted to his faithful friend, Ezzelino III da Romano at Verona.

In the 13th century the Counts of Tyrol took advantage of the confused situation to carve out a conspicuous power as a Vogt for himself, much at the loss of the Bishops of Chur, Brixen, the Archbishopric of Salzburg and Trento itself.

Count Meinhard II of Tyrol (1258–1295), also Duke of Carinthia from 1286, totally subjected the bishops of Trento and Brixen under his power, and reorganized his new state along the more modern lines inspired to those of other Italian principalities.

In the following year, the bishops struggled in order to thwart the growing power of the Habsburgs, and in the end the principality reduced to an effective subjugation to Austrian authority.

The rebellers were led by Michael Gaismayr, who had devised a complex plan of liberation of all the territories of Brixen and Trento and program of social freedom based on equalitary principles (Landesordnung).

The rebels, however, lacked organisation and were easily suppressed in 1526 by Austrian mercenaries and by the bishop Bernardo Clesio, who ferociously exterminated them in the battles of the Eisack valley and Sterzing.

The introduction of the Counter-Reformation in the principality brought also a general recover of the Italian language over the German one, as the Protestant ideas had found more followers in the German-speaking population.

This however did not mean the loss of his semi-independent status, and several outstanding results were obtained anyway — the balance active of 1683, the completion of the Castello del Buonconsiglio in Trento, and the drying of the marshes in the Adige valley.

Following the 1801 Treaty of Lunéville, the prince-bishopric in 1803 was secularized as the Principality of Trent, later part of the County of Tyrol, an Alpine crown land of the Austrian Empire from 1804.

It however remained a part of the Tyrolean crown land (Welschtirol), even after Austria had to cede the adjacent Veneto region after the Third Italian War of Independence in 1866.