INSUBRIA

'Insubria' is a historical-geographical region which corresponds to the area inhabited in the past by the Insubres, a Celtic people which dwelt in the 4th-5th century B.C. in the area of pre-Alpine lakes and Milan. Polibius claims the Insubres founded the city of Milan around 600 B.C. Secondarily the name can refer to the Duchy of Milan (1395-1810).
The name Insubres is visible in the middle portion of the Tabula Peutingeriana. Therefore for several centuries this name stood for an area stretching approximately between the Adda river in the East and the Sesia river in the West, and between the San Gottardo Pass in the North and the Po river in the South. Thus it was a synonym of the Milan region and the countryside areas gravitating towards it.
The symbol of Insubria (when conceived as the Duchy of Milan) is the Milanese Ducal flag, the Visconti child-swallowing serpent quartere