Between Italy on the one hand, and the great commands on the Rhine and Danube on the other, there are four passes which were known at that time to lead through the alps, viz. that which skirts the Ligurian sea, that which passes through the land of the Taurini (the Mont Genèvre), that through the territory of the Salassi (the Little St. Bernard), and that by way of Rhaetia (the Brenner).

There was drawn a girdle of small governorships, which were not merely all filled up by the emperor, but were also filled up throughout with men not belonging to the senate. Italy and the province of southern Gaul were separated by the three small military districts of the Maritime Alps (department of the Maritime Alps and the province of Cuneo), the Cottian Alps with Segusio ( Susa) as its chief town, and probably the Graian Alps ( East Savoy). Among these the second, administered by the already named cantonal prince, Cottius, and his descendants for a time under the form of clientship, was of most importance, but they all possessed a certain military power, and were primarily destined to maintain public safety in the territory concerned, and above all on the important imperial highways traversing it.

Alpes Cottiae was a province of the Roman Empire, one of three small provinces straddling the Alps between modern France and Italy. Its name survives in the modern Cottian Alps. In antiquity, the province's most important duty was the safeguarding of communications over the Alpine passes. Alpes Cottiae was bordered by Gallia Narbonensis to the west, Alpes Maritimae to the south, Italia to the east, and Alpes Graiae to the north. The provincial capital was at Segusio (modern Susa in Piedmont).

The province had its origin in the kingdom controled by Donnus, ruler of the local Ligurian tribes of the area in the middle of the first century B.C., and was named after his son and successor Cottius, whose realm was integrated into the Roman imperial system under Augustus. Initially, Cottius and his own son of the same name after him continued to hold power as client kings; afterwards, under Nero a procurator was appointed and it officially became a Roman province. The governors of the province were prefects from the Equestrian order.

Settlements in Alpes Cottiae included:
Ocelum (Lesseau)
Segusio (Susa) (capital)
Scingomagus (Exilles)
Caesao (Cesana Torinese)

Tilmann Bechert:
Die Provinzen des römischen Reiches:
Einführung und Überblick. von Zabern, Mainz 1999.