In the centuries that followed, Rome was invaded, in turn, by the Vandals, the Goths and the Longobards. The Longobard king, Liutprand (712-744), firmly wanted to conquer Italy to free her from the Byzantine occupation.
During his attempt, Liutprand was stopped in Sutrium, about 50 km away from Rome, by Pope Gregorius II (715-731) who convinced him to withdraw and donate the castle of Sutrium to the Church (“to the apostles Peter and Paul”). This happened in 728. Historians consider this date to be the beginning of the temporal power of the Church and, therefore, the beginning of the Papal State.
Liutprand repeated his enterprise in 742, but was stopped by Pope Zachary II (741-752) and, again, donated other castles to the Church.
Pope Zachary II and Hadrian I (772-795) thus created a network of colonial settlements which employed local militia positioned at a mean distance of 10 miles from the city and which constituted a protective barrier. In other words, it was a sort of “belt” around Rome which corresponded, approximately, to the present-day round-route, with two towers positioned, alternately, either on the inner or outer side of it.
These settlements had churches, mills and granaries and were called domuscultae. Around them, there were homesteads inhabited by the so called familiares Sancti Petri who occasionally became members of the Pontifical army since the Pope did not have one of his own in Rome.
Civil wars and the War of Investitures provoked the weakening of the domuscultae which were transformed into curtes in the 10th century, and later became simple, rural fenced estates.