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.
Papal States under Pope Pius IX
After the Second Italian War of Independence, much of northern Italy was unified under the House of Savoy's government; in the aftermath, Garibaldi's expedition of the Thousand overthrew the Bourbon monarchy in the Kingdom of the Two Sicilies. Afraid that Garibaldi would set up a republican government in the south, the Sardinians petitioned Napoleon for permission to send troops through the Papal States to gain control of the Two Sicilies, which was granted on the condition that Rome was left undisturbed. In 1860, with much of the region already in rebellion against Papal rule, Sardinia conquered the eastern two-thirds of the Papal States and cemented its hold on the south. Bologna, Ferrara, Umbria, the Marches, Benevento and Pontecorvo were all formally annexed by November of the same year, and a unified Kingdom of Italy was declared. The Papal States were reduced to the Latium region surrounding Rome, raising the Roman Question.