From the fall of the Roman Empire to the formation of a free comune
The fall of the Roman Empire was followed by the occupation by the Goths (476-553), to which the Byzantines placed an end with a war between the Generals of the Emperor Justinian, Belisarius and Narsete, and the Gothic Kings Theodatus, Vitige, Totila and Treaia. The Gothic War (535-553) brought about a significant decrease in the Italic population: Cortona was then reduced to a desert land and the Municipality disappeared as well as probably the Diocese. Further devastations followed with the occupation of the Longobards, still in conflict with the Byzantines, especially along the border of the Byzantine corridor going from Ravenna to Rome. Cortona was not far from the border of that corridor and was forced to bear the burden of abuse and devastation and the aftermath of the conflicts between the Aryan Longobards and the orthodox Byzantines. It is not difficult to imagine the state of misery and desolation into which the city must have fallen. It was Charlemagne who put an end to the Longobard occupation in 774.
Despite these tragic events, there is a document from the year 970 written in the diary of Siegbert, a German diarist traveling though Italy that tells of a beautiful and ornate basilica he had seen in the area of the city on the tomb of the martyr Vincenzo. The remains of this basilica are today private property, but some of the relics are conserved in the Etruscan Academy Museum, confirming the German diarist’s report. In the 13th century the first documents after the Dark Ages appear. From these documents we know that Cortona is a free city among many others in Italy and that it is in the religious realm of the Diocese of Arezzo. This meant that all religious matters depended on the bishop of Arezzo who had also a political power over Cortona, since the events in Arezzo at that time made the bishop the most important political figure. At that time Arezzo, the bishopric, minted a coin which had the likeness of its first bishop on one side, the martyr Donato. The coin of Perugia also had a portrait of its first bishop, the martyr Ercolano. Cortona, which was not a bishopric, minted however its own coin: on the front it had the portrait of a bishop with a pointed cap and staff framed with the word "Vincentius" and on the back a cross with the inscription "De Cortona". Cortona was ruled by a Podestà, a Captain of the People, by the Community Consul and the Chancellors of the Arts.