It consists of the valleys of the river Mella and its tributaries, north of the city of Brescia.
[1] The name originates from the ancient Rhaetian people, the Trumpilini, the conquest of which by part of the Romans was more difficult than that of Cenomani of Brixia.
The presence in the high part of the valley of mineral veins promoted since the antiquity an important mining activity.
For this reason, under the Venetian domination, the valley was given a special autonomy and a lighter tax regime.
Suburban sprawl continues for more than 20 kilometers northwards although the area is not densely populated.