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.
The last will and testament of Doge Giustiniano Particiaco, ordering, among other things, the construction of a new church next to the ducal palace where the newly procured remains of St. Mark the Evangelist ought to be deposited.
The first pact between the Venetian neighbors in the Kingdom of Italy, represented by Emperor Lothar I, and the Duchy of Venice, represented by Doge Pietro Tradonico, sanctioning mutual aid in campaigns against the Slavs, defining the rights over the use of land and numerous aspects related to trade as well as the modalities of justice administration.
Emperor Lothar I confirms the Venetian possessions in the Empire.
Venice, represented by Doge Orso I Participazio, and the Patriarchate of Aquileia, represented by Patriarch Walpert, sign a treaty according to which the Venetian Doge agrees not to block the Aquileian port Pylum, but only under the condition that the patriarch stops with all the hostilities directed against the Church of Grado and exempts the Venetians from all the tolls on his territories, according to the old customs.
Due to fair treatment and continuous protection, the city of Koper, represented by a locopositus, scabini, the protector of the people (advocatus totius populi) and many others, freely promise an annual gift of one hundred amphorae of wine to the Venetian Doge Pietro II Candiano, to be paid every year within ten days of the harvest, guarantee protection to all Venetians in their city, and prompt debt recovery.
Following a dispute between the Venetians and Istrians, one that resulted in the embargo on all trading between Istria and Venice, Margrave Winther, together with the people and the bishops of Istria, promise to cease all hostilities towards the Venetians, not to usurp or occupy the properties of the Patriarchate of Grado or Venetian bishoprics in the region, to regularly take cognizance of and adjudicate the complaints lodged by the Venetians against defaulting debtors from Istria, to abolish all the newly instituted duties and only charge the customary fees of a docking tax and a market fee, and to promptly inform the Venetians in case the king of Italy plans any offensive against them so that they could safely repatriate.
Thanks to the mediation of Marino, the patriarch of Grado, Lupus II, the patriarch of Aquileia, manages to reach a peace accord with Venice, represented by Doge Pietro III Candiano, but only under the condition that all the hostilities directed against Grado immediately stop and that the patriarch promises to inform Venice of any hostile plans directed against it.
Doge Pietro IV Candiano reenacts a decree forbidding slave trading, originally promulgated by Doge Orso I Participazio, imposing further restrictions on dealings with slavers and regulating postal communication with the Byzantine imperial court.
Emperor Otto I donates Izola in Istria to the Venetian Vitale Candiano.
Emperor Otto II confirms the purchase of Izola, sold by Vitale Candiano to Patriarch Rodoald of Aquileia.
The city of Koper renews its pact of fealty to the doge and the city of Venice, promising the security of all Venetians in their city, the remission of duties of transport and commerce, the payment of the customary tribute of one hundred amphorae of wine every year, judicial autonomy, perpetual peace and alliance even in case of war against other Istrian communities.
Venetian Doge Pietro II Orseolo departs with his navy on a military expedition against Croats and Narantines in Dalmatia; on his journey, the doge stops at Poreč and Pula where he is cordially greeted by the bishops, clergy, and citizens of these Istrian cities (narrative account from John the Deacon’s Istoria Veneticorum).
As Venetian Doge Otto Orseolo and his brother Urso, the patriarch of Grado, are banished from Venice and find shelter in Istria, Poppo, the patriarch of Aquileia, uses the opportunity and military invades Grado, snatching away numerous relics and the patriarchal treasury; the Venetians soon strike back and retake Grado, expelling the Aquileian forces (narrative accounts from three different chronicles).
Following the Synod of Rome, convened to resolve the recently rekindled conflict between the patriarchs of Aquileia and Grado, Pope Benedict IX writes to Urso, the patriarch of Grado, informing him of the Synod’s decision to support the cause of his church against the Aquileian Patriarch Poppo, who had recently launched a second military invasion of Grado before his untimely death; the pope confirms the metropolitan status together with the ecclesiastical and secular jurisdictions of the Patriarchate of Grado, dubbed “New Aquileia” for the very first time in an authentic papal document.
Doge Domenico Selvo confirms the donation of various tributes and incomes to the Patriarchate of Grado, originally donated by his predecessor Doge Domenico I Contarini.
The people of Koper and Izola swear an oath of fealty to the doge and the Commune of Venice, promising to arm one galley whenever Venice would embark on a military campaign with fifteen or more galleys, military aid for any Venetian military endeavor in the Adriatic, in the zone between Dubrovnik, Venice, and Ancona, guaranteeing the safety of all the Venetians in their city, and promising to observe the same ducal laws on grain trade as Venetians.
The people of the Commune of Pula swear fealty to Doge Pietro Polani and to the Commune of Venice, promising military aid in the form of arming one galley per every fifteen Venetian galleys during Venetian military campaigns, to support the Venetian military efforts in the Adriatic, in the zone between Dubrovnik, Venice, and Ancona, and to defend Venice if they see hostile ships approaching their city, exempting the Venetians from all the dues and tolls in their city except the harbor tax (portaticus), guaranteeing safety and judicial autonomy in disputes between Venetians and the citizens of Pula, gifting the doge and the Commune of Venice with a house by the city’s gates, and agreeing to swear the same promise of fealty to every new doge upon his consecration; the doge and the Commune of Venice agree to defend the Commune of Pula against their enemies and to treat the citizens of Pula as their own citizens in Venice.
Five Istrian communities – Pula, Rovinj, Poreč, Novigrad and Umag – pledge their fealty to the doge of Venice and his successors, promising military support, a variety of symbolic tributes to St. Mark, the patron saint of Venice, and to the doges, guaranteeing the safety of all the Venetians in their jurisdictions and abolishing all the dues for Venetian traders.
The people and the clergy of Pula agree to a final settlement with Venice whereby they fully acknowledge their fault for the military actions directed against them and renounce all their claims for further recompense and restitutions.
The consuls and the people of Pula write to the patriarch of Aquileia Ulrich II, informing him that they are aware of the emperor’s arrival (in the vicinity of Venice) and that the imperial assembly will be convened on May 22; therefore, they ask him to take up with the emperor their complaints against the Venetians, who treat them as their subjects.
In response to the plea of the citizens of Koper, Doge Orio Mastropiero and the Commune of Venice issue a privilege to Koper, constituting it the only licensed port for salt trade in entire Istria, from Pula to Grado, and granting it a galley by which the citizens of Koper are to oversee the salt trade along the western coast of Istria; the privilege is accorded for twenty-nine years.
On their way to engage the inimical Pisan fleet, the Venetian armada stops in Pula to receive additional military support; met with refusal, the Venetian fleet attacks Pula, razes its walls, and sacks the city; defeated, Pula reacknowledges fealty owed to Venice (narrative account as featured in the so-called Annales Venetici brevis).
Venetian Doge Enrico Dandolo accepts the demands of Aquileian Patriarch Peregrine II and agrees to offer help – mainly political and diplomatic, but also, if need be, military – against the Commune of Treviso, but asks for a number of concessions in return, all of which are granted by the patriarch with the sole exception of military aid.
Faced with the might of the Venetian navy and the crusading army on their way to Constantinople, the people of Trieste ask forgiveness from Doge Enrico Dandolo for their past transgressions, and promise fealty to the doge and the Commune of Venice, guaranteeing the safety and duty-free trading for the Venetians throughout their jurisdictions, aid in combating piracy in the zone from Rovinj northward, a tribute of fifty urns of wine paid yearly on St. Martin’s feast day and transported to the ducal palace in Venice, and generally to perform all the duties promised by other Istrian communities.