Scriptores

In the midst of the war between the Roman Empire under Emperor Justinian I and the Ostrogoths in Italy, the Roman general Belisarius plans the siege of the Ostrogothic capital Ravenna; The Po valley is blocked as Belisarius commands Vitalius, magister militum per Illyricum, to depart with his army from Dalmatia and subject the Ostrogothic towns of regio Venetia; traditionally taken as marking the Byzantine conquest of Ostrogothic Istria and the beginning of the centuries-long rule of the Eastern Roman Empire in Istria (narrative accounts from Procopius of Cesearea's History of the Wars).

Belisarius and Vitalius, the generals of Emperor Justinian I's army, draft new soldiers across Thrace and Illyricum as they prepare for a new assault against the Ostrogoths in Italy; they stop in Pula to regroup before sailing to Ravenna to engage the enemies (narrative accounts from Procopius' History of the Wars).

Emperor Justinian I has Pope Vigilius I consecrate Maximian, a deacon from Pula, as the new bishop of Ravenna; once installed as bishop, Maximian embarks on several architectural projects, including the building of the Santa Maria Formosa church in Pula (narrative accounts from the Life of Saint Maximian written by Agnellus of Ravenna in his Book of the Pontiffs of the Church of Ravenna).

Emperor Justinian I appoints his cousin Germanus as the commander-in-chief of his army fighting against King Totila in Italy; the promise of a renewed war effort against the Ostrogoths under a famous military commander encourages men across the region to rally under imperial banner as they journey to Istria, awaiting the arrival of Germanus (narrative accounts from Procopius of Cesearea's History of the Wars).

A poem composed by Venantius Fortunatus to a Vitalis, a bishop of Ravenna, traditionally identified as Maximian of Ravenna, but also as bishop Vitalis of Milan, bishop Vitalis of Altino, or even an eponymous, otherwise undocumented bishop of Pula.

Venantius Fortunatus composes a poem in celebration of the construction of the church of St. Andrew, built by a Vitalis, the bishop of Ravenna (most probably a laudatory nickname for Bishop Maximian).

Lombards under King Alboin invade Italy and conquer Friuli; Gisulf I, Alboin's nephew, is made the ruler (duke) of Friuli; Paulinus, the incumbent patriarch of Aquileia, flees from Aquileia due to the invasion and finds shelter in Grado where he hides the treasury of his Church as well (narrative account from Paul the Deacon's History of the Lombards).

Pope Benedict I officially sanctions the transfer of the episcopal see from Aquileia to Grado; 11th-century forgery included in the Chronicle of Grado.

Lombard King Authari dispatches an army led by duke Ewin of Trento to attack Istria, at the time a Byzantine province. Following successful Lombard attacks, a one-year peace is negotiated between the warring parties (narrative account from Paul the Deacon's History of the Lombards). 

Following the death of Aquileian patriarch Helias, his successor, Patriarch Severus, together with three other bishops (including the bishop of Poreč, John) are imprisoned in Ravenna by the Byzantine exarch Smaragdus; in order to buy their freedom, the prelates agree to condemn the Three Chapters and reunite with Rome, a move that greatly angers other bishops in the ecclesiastical province of Aquileia. Finally, a synod is held in Marano (591) whereby Patriarch Severus is forced to formally acknowledge the error of his ways in supporting the condemnation of the Three Chapters (narrative accounts from Paul the Deacon's History of the Lombards).

The regions of Ravenna, Grado, and Istria are ravaged by the so-called Justinianic plague as Agilulf, King of the Lombards, makes peace with the Avars (narrative accounts from Paul the Deacon's History of the Lombards).

Perpetual peace is celebrated between the Lombard King Agilulf and the Avar Khagan as Byzantine Istria is attacked by the combined forces of the Lombards, Avars, and Slavs (narrative account from Paul the Deacon's History of the Lombards).

Following the death of Aquileian patriarch Severus, two new patriarchs are ordained: John, supported by the Lombards and with his seat in Aquileia; and Candidianus, supported by the Romans (Byzantines) with his seat in Grado - the definitive and official split of the patriarchate of Aquileia into two patriarchal sees (narrative account from Paul the Deacon's History of the Lombards).

Lombard King Agilulf renews peace with the Byzantine Emperor and the Franks as the Slavs ravage across Istria (narrative accounts from Paul the Deacon's History of the Lombards).

Pope John IV dispatches abbot Martin to journey across Dalmatia and Istria to ransom the captives (imprisoned, one would assume, by the still pagan Slavs) and return the relics of the saints from these endangered places to Rome; narrative account from the Book of the Popes (Liber pontificalis).

De terminatione provinciarum Italiae – Istria together with Venice featured as the first region of Italy in an early medieval catalogue of the provinces of Italy.

Ansfrit of Ragogna rebels against Rodoald, the Lombard duke of Friuli, and conquers his duchy as Rodoald flees to Istria from where he sails to Ravenna and finally reaches King Cunipert in Pavia (narrative account from Paul the Deacon's History of the Lombards).

Under Lombard King Cunipert, the Synod of Pavia takes place where the representatives of the schismatic clergy of the ecclesiastical province of Aquileia officially accept the decrees of the 5^th Ecumenical Council (Constantinople II) and finally desist from their schism; narrative account from the contemporary "Poem on the Synod of Pavia" (Carmen or Rythmus de Synodo Ticinensi).

Istria as described in the chapters of Cosmography, penned by the anonymous Ravenna Cosmographer (Anonymus Ravennas), including the region's rendition on the famous Peutinger's Map (Tabula Peutingeriana).

Lombard King Aistulf defeats and captures Eutychius, the Exarch of Ravenna, conquering the Byzantine Exarchate in Italy and further expanding the Lombard Kingdom over Comacchio, Ferrara and Istria (narrative account from the Salerno Chronicle).

Late 8^th-century poem lamenting the destruction of Aquileia at the hands of the Huns in the mid-5^th century, composed either by Paulinus II of Aquileia (ⴕ 802) or Paul the Deacon; the poem was later used by Venetian authors to argue that Aquileia had never been restored following this destruction and that Grado, therefore, succeeded it as the capital of the ecclesiastical province of Venetia et Histria.

Narrative sources on the events of 788 that resulted, among a variety of other things, with Istria being incorporated into the Frankish kingdom.

A poem dedicated to the memory of the late Duke Eric of Friuli, composed by Patriarch of Aquileia Paulinus II.

Emperor Louis the Pious deposes several marcher officials – including Baldric, the duke of Friuli – from their offices due to their military impotence. As a result of Baldric’s deposition, the March of Friuli – which included Istria – is divided into four counties governed by their respective counts.

A poem composed in response to the Synod of Mantua (6^th of June, 827), arguing that Aquileia, the old metropolitan see of the ecclesiastical province Venetia et Histria, was so thoroughly destroyed by barbarians (Attila, the Avars, Lombards and Goths) that it was never rebuilt; thus, the metropolitan see transferred to "the Venetians" and Aquileia was demoted to a status of a mere parish.