It is commonly identified with an unnamed new, "well-fortified" city, recorded by the historian Procopius (De Aedificiis, IV.1.39–42) as having been built by the Byzantine emperor Justinian I (r. 527–565) for the inhabitants of ancient Euroia,[1][2] but archaeological evidence for this is lacking; indeed, early 21st-century excavations have brought to light fortifications dating to the Hellenistic period (4th–3rd centuries BC), the course of which was largely followed by the later Castle of Ioannina.

[3] The name Ioannina appears for the first time in 879, in the acts of the Fourth Council of Constantinople, which refer to one Zacharias, Bishop of Ioannine, a suffragan of Naupaktos.

[2] In the treaty of partition of the Byzantine lands after the Fourth Crusade, Ioannina was promised to the Venetians, but in the event, it became part of the new principality of Epirus, founded by Michael I Komnenos Doukas.

[4] Following the assassination of the last native ruler, Thomas I Komnenos Doukas by his nephew, Nicholas Orsini, in 1318, the city refused to accept the latter and turned to the Byzantines for assistance.

[7] Under the regime of Thomas II Preljubović (1367–1384), the citizens and the local Church suffered greatly: Thomas confiscated property in favour of his Serb followers, and drove the Metropolitan Sebastianos to exile; nevertheless, he was able to repel successive attempts by the Albanian chieftains Peter Losha and John Bua Spata to capture the city, most notably the great surprise attack of 1379, whose failure the Ioannites attributed to intervention by their patron, Saint Michael.

[10] This privileged position lasted until 1611, when the city was engulfed by the peasant revolt led by Dionysius the Philosopher, the Metropolitan of Larissa.