The Papal States, officially the State of the Church, were a conglomeration of territories on the Apennine Peninsula under the direct sovereign rule of the Pope from 756 until 1870. They were among the major states of Italy from the 8th century until the Unification of Italy, between 1859 and 1870.

Sovereignty can generally be defined as supreme authority. Sovereignty entails hierarchy within the state, as well as external autonomy for states. In any state, sovereignty is assigned to the person, body or institution that has the ultimate authority over other people in order to establish a law or change existing laws. In political theory, sovereignty is a substantive term designating supreme legitimate authority over some polity. In international law, sovereignty is the exercise of power by a state. De jure sovereignty refers to the legal right to do so; de facto sovereignty refers to the factual ability to do so. This can become an issue of special concern upon the failure of the usual expectation that de jure and de facto sovereignty exist at the place and time of concern, and reside within the same organization.