Complex sentence: Insubria is a historical-geographical region which corresponds to the area inhabited in Classical antiquity by the Insubres; the name can also refer to the Duchy of Milan (1395--1810).
Split into simpler sentences: Insubria is a historical-geographical region which corresponds to the area inhabited in Classical antiquity by the Insubres. Secondarily the name can refer to the Duchy of Milan (1395--1810).