Pope Stephen II in the context of "Coronation of the French monarch"

The Papal States (/ˈpeɪpəl/ PAY-pəl; Italian: Stato Pontificio; Latin: Dicio Pontificia), officially the State of the Church, were a conglomeration of territories on the Italian peninsula under the direct sovereign rule of the pope from 756 to 1870. They were among the major states of Italy from the 8th century until the unification of Italy, which took place between 1859 and 1870, culminating in their demise.

The state was legally established in the 8th century when Pepin the Short, king of the Franks, gave Pope Stephen II, as a temporal sovereign, lands formerly held by Arian Christian Lombards, adding them to lands and other real estate formerly acquired and held by the bishops of Rome as landlords from the time of Constantine onward. This donation came about as part of a process whereby the popes began to turn away from the Byzantine emperors as their foremost temporal guardians for reasons such as increased imperial taxes, disagreement with respect to iconoclasm, and failure of the emperors, or their exarchs in Italy, to protect Rome and the rest of the peninsula from barbarian invasion and pillage.

The Donation of Pepin, or Donation of Pippin, was the transfer of Frankish territory in central Italy to Pope Stephen II made by Pepin the Short, King of the Franks, in 756. Credited with "effectively establishing the temporal authority of the papacy," the Donation took place amid the Byzantine Empire's decline in Italy and marked both "an important moment in the papal–Carolingian alliance" and an "important step" in the formation of the Papal States. With the fall of the imperial capital in Italy, Ravenna, to Aistulf, King of the Lombards in 751, "any semblance of imperial protection for Rome" had evaporated and the pope, who had technically been a Byzantine subject to this point, turned to Pepin for assistance. Pepin invaded Italy and, following an initial victory in 755, he decisively "defeated Aistulf and imposed a peace on him" in 756.

Pepin had promised Italian lands to Stephen II at a meeting in Quierzy, France in April 754. While this earlier promise is "often identified as the Donation," it may have been only verbal and "does not exist in written form." Papal accounts of the 754 promise state that Pepin "granted the pope the exarchate, including Ravenna, and the Roman duchy." In 756, the "Confession of St. Peter," a document listing the cities involved in the Donation, was "placed on the altar of Old St. Peter’s Basilica in Rome" along with "keys of the cities and territories in central Italy." The Confession document was created "following Pippin’s second invasion of Italy to assist the pope." After his initial invasion in 755, Pepin concluded the First Peace of Pavia, but Aistulf "refused to abide by" this agreement and attacked Rome. Pepin then defeated Aistulf again, imposing "heavy penalties" with the Second Peace of Pavia in 756.

The House of Orsini is an Italian noble family that was one of the most influential princely families in medieval Italy and Renaissance Rome. Members of the Orsini family include five popes: Stephen II (752–757), Paul I (757–767), Celestine III (1191–1198), Nicholas III (1277–1280), and Benedict XIII (1724–1730). The family also included 34 cardinals, numerous condottieri, and other significant political and religious figures. The Orsini are part of the Black nobility who were Roman aristocratic families who supported the Popes in the governance of the Papal States.

In the history of the Papacy, the Frankish Papacy (756–857) was a period marked by a shifting of influence from the Byzantine Empire (i.e. the Byzantine Papacy) to that of the kings of the Franks. Pepin the Short (ruled 751–768), Charlemagne (r. 768–814) (co-ruler with his brother Carloman I until 771), and Louis the Pious (r. 814–840) had considerable influence in the selection and administration of popes. The "Donation of Pepin" (756) ratified a new period of papal rule in central Italy, which became known as the Papal States.

This shift was initiated by the Lombards conquering the Exarchate of Ravenna from the Byzantines, strengthened by the Frankish triumph over the Lombards, and ended by the fragmentation of the Frankish Kingdom into West Francia, Middle Francia, and East Francia. Lothair I continued to rule Middle Francia which included much of the Italian peninsula, from 843 to 855.