[4] In the Early Middle Ages, the territory of the Byzantine province of Dalmatia reached in the North up to the river Sava, and was part of the Praetorian prefecture of Illyricum.

In the middle of the 6th and the beginning of the 7th century began the Slavic migration, which caused the Romance-speaking population, descendants of Romans and Illyrians (speaking Dalmatian), to flee to the coast and islands.

[9] Via conquests, the Republic of Venice, from the 9th century until 1797, when it was conquered by Napoleon, extended its dominion to coastal parts of Istria and Dalmatia.

[21] However, after the Third Italian War of Independence (1866), when the Veneto and Friuli regions were ceded by the Austrians to the newly formed Kingdom Italy, Istria and Dalmatia remained part of the Austro-Hungarian Empire, together with other Italian-speaking areas on the eastern Adriatic.

[22] During the meeting of the Council of Ministers of 12 November 1866, Emperor Franz Joseph I of Austria outlined a wide-ranging project aimed at the Germanization or Slavization of the areas of the empire with an Italian presence:[23] His Majesty expressed the precise order that action be taken decisively against the influence of the Italian elements still present in some regions of the Crown and, appropriately occupying the posts of public, judicial, masters employees as well as with the influence of the press, work in South Tyrol, Dalmatia and Littoral for the Germanization and Slavization of these territories according to the circumstances, with energy and without any regard.

[29] Bartoli's evaluation was followed by other claims that Auguste de Marmont, the French Governor General of the Napoleonic Illyrian Provinces commissioned a census in 1809 which found that Dalmatian Italians comprised 29% of the total population of Dalmatia.

[34] In Rijeka the Italians were the relative majority in the municipality (48.61% in 1910), and in addition to the large Croatian community (25.95% in the same year), there was also a fair Hungarian minority (13.03%).

The policy of collaboration with the local Serbs, inaugurated by the Tsaratino Ghiglianovich and the Raguseo Giovanni Avoscani, then allowed the Italians to conquer the municipal administration of Dubrovnik in 1899.

[37] These interferences, together with other aiding actions to the Slavic ethnic group considered by the empire more faithful to the crown, exacerbated the situation by feeding the most extremist and revolutionary currents.

In 1915, Italy declared war on the Austro-Hungarian Empire,[38] leading to bloody conflict mainly on the Isonzo and Piave fronts.

[39] In a deal to bring Italy into the war, under the London Pact, Italy would be allowed to annex not only Italian-speaking Trentino and Trieste, but also German-speaking South Tyrol, Istria (which included large non-Italian communities), and the northern part of Dalmatia including the areas of Zadar (Zara) and Šibenik (Sebenico).

[39] In November 1918, after the surrender of Austria-Hungary, Italy occupied militarily Trentino Alto-Adige, the Julian March, Istria, the Kvarner Gulf and Dalmatia, all Austro-Hungarian territories.

[40] Furthermore, after World War I and the fall of the Austro-Hungarian Empire, 10,000 Italians in the Governatorato took Yugoslav citizenship so they could remain and be accepted by the new Yugoslavian state.

[41] In 1939 Italy conducted a covert census of the non-Italian population (Croats and Slovenes) in Istria, Kvarner, Zadar, Trieste and Gorizia.

In 1942, 4020 Italians lived in these newly annexed areas: 2,220 in Spalato (Split), 300 in Sebenico (Šibenik), 500 in Cattaro (Kotor) and 1000 in Veglia (Krk).

After the conquest of Napoleon and his donation of the territories that belonged to the ancient Venetian Republic to the Habsburg Empire, these Italian populations had to undergo Austro-Hungarian power.

After the First World War and the D'Annunzio enterprise of Fiume many of the Istrian and Dalmatian territories passed to the Kingdom of Italy, strengthening the Italian majority in Istria and Dalmatia.

For fear of ethnic retaliation by the Slavic populations, the majority of Italians from Istria and Dalmatia poured into a real exodus towards Trieste and Triveneto.

Subsequently, many of them were transferred by the authorities of the Italian Republic to southern Lazio and Sardinia where they formed numerous local communities.

According to Maurizio Tremul, president of the executive council of the UI, the census data in the part in which it is asked to declare the ethnicity are a bit distorted due to a "reverential fear" towards the censors who do not use Italian nor bilingual forms.

The indigenous Venetian populations (north-western Istria and Dalmatia) and the Istriot-speaking peoples of the south-western Istrian coast are included in this Italian ethnic group.

A local Community of Italians was formed in Zagreb, which mainly brings together among its members recent immigrants from Italy, as well as a fair number of Italian-speaking Istrians who have moved to the capital.

During Fascism these Istrorumeni were considered ethnically Italian because of their mixing during the Middle Ages with the descendants of the Ladin populations of Roman Istria, and they were guaranteed elementary teaching in their native language.

Some Venetian or Italian-speaking families are still present on the island of Lesina, where the creation of an Italian Union headquarters - named after the Lesignano writer Giovanni Francesco Biondi - for all Italian-Croatians of Dalmatia has been promoted Southern.

Pelagosa (and its small archipelago) was populated together with the nearby Tremiti islands by Ferdinando II of the Kingdom of the Two Sicilies in 1843 with fishermen from Ischia, who continued to speak the dialect of origin there.

The City of Fiume, within the scope of its possibilities, ensures and supports the educational and cultural activity of the members of the indigenous Italian minority and its institutions.

After considerable government opposition,[66][67] with the imposition of a national filter that imposed the obligation to possess Italian citizenship for registration, in the end in 2013 it was opened hosting the first 25 children.