History of Sardinia
In the Early Middle Ages, through barbarian movements, the waning of the Byzantine Empire influence in the western Mediterranean and the Saracen raids, the island fell out of the sphere of influence of any higher government. This led to the birth of four kingdoms called "Judicates" (Latin: "Judicati"; Sardinian: "Judicados") in the 8th through 10th centuries. Falling under papal influence, Sardinia became the focus of the rivalry of Genoa and Pisa, the Judicates and the Crown of Aragon, which eventually subsumed the island as the Kingdom of Sardinia in 1324. The Kingdom was to last until 1718, when it was ceded to the Piedmontese House of Savoy; later, in 1861, it would thus become the Kingdom of Italy and finally in 1946 the Italian Republic.
Province of Sondrio
The Peace of Westphalia (1648) secured peace in the region and granted the region to the Canton of Graubünden. In 1797, the Republic of Valtellina was formed but was quickly conquered by the French to become a component of the Cisalpine Republic client state. The Congress of Vienna (1815) Sondrio and Valtellina as a province of the Austrian Kingdom of Lombardy–Venetia.
Lombardy–Venetia was absorbed into the Kingdom of Italy in 1866.