As a nation state, Italy has emerged only in 1871. Until then the country was politically divided into a large number of independant cities, provinces and islands. The currently available evidences point out to a dominant Etruscan, Greek and Roman cultural influence on today's Italians.
To make it short, as Sicily was a possession of foreign (spanish) kings, they appointed a viceroy who ruled in their place, but under their control. Of course, they were usually nobles. Here is a list of Sicilian viceroys: