The Holy Roman Empire
In the central part of Europe, one of the regions formerly part of the Roman Empire became known as the "Holy Roman Empire." Although it did not include the city of Rome, it took this name because the most important authority was not a king but the Catholic Church, headed by the pope in Rome.
The Holy Roman Empire began in the year 1356, when the pope issued the Golden Bull, which authorized seven of the most prominent nobles in the region to meet and to choose from among them one to serve as "emperor" and to rule over the region. Because he would have his authority from the pope, the emperor was not only the overseer of these lands but also the temporal arm of the Catholic Church -- in effect, the leader of the Crusades.
Unlike for example in France , these various principalities were not united into a single country under a single monarch, in the sense that the Emperor had very limited power within each of the regions constituting the Empire.