They were of Aryan religion. The conquest was violent. After the occupation the country was divided in many little state, but the Longobards do not succeed to conquer those occupied by the Byzantine. Pavia becomes the Capital of the Longobard reign. Their economy was based on agriculture and breeding: the cities decay, the territory become rich of small fortified settlements, some with enclosure walls with elliptical form others constituted only by a watchtower, from which the invaders exercise the control on the Italic population. In the 584 Autari come elect king of the Longobards; years 591-616 Reign of Agilulfo. In the 603 Gregorio Magno I (Pope, 590-604) concludes the peace between Longobards and Byzantine and so started to the process of conversion to the Catholicism of the Longobard people. 636-652 Reign of Rotari. In the 643 promulgation of the 'Edict of Rotari', first coding for the barbaric right. 712-744 Reign of Liutprando.
In the first half of VIII° century the Longobards tried to take advantage of the conflicts between the Church and the Roman aristocracy whom make of all for replace the Byzantine: the Esarca was victim of a murder, between the 733 and the 742 Liutprando occupies the Esarcato. 749 Astolfo, new king of the Longobards, occupies Ravenna and Pentapoli (750-751) and attacks the territories of the Church. But this last one effectively opposed great resistance to the Longobard expansion and the invaders were forced to donate the Church the important castle of Sutri (729), that will constitute the first nucleus of the Territory of S.Pietro. In the 754, called fro help from Pope Stefano II (753) comes down in Italy the king of the French Pipino il Breve, that forces Astolfo, with the peace of Pavia , to give back to the Pope the lands removed to the Byzantine. But in the 756 Astolfo resumes his attacks and besieges Rome.
Pipino il Breve comes back down in Italy, defeats again Astolfo and, with according to treaty of Pavia, obligates the Longobards to renounce at the Esarcato and at Pentapoli, that were turned both to the Pope (donation of Pipino). The State of the Church extends itself now from the Duchy of Rome to the Marches and the Romagna. 756-774 reign of Desiderio that in the 772 invades one more time the state of the church. 774 last coming in Italy of the French, calls from Pope Adrian and guided by Carlo Magno, against the Longobards. Desiderio was imprisoned and Carlo comes king of the French and Longobards. In the year 800 Carlo Magno becomes Emperor of Rome: birth of the Sacred Roman Empire.