According to homeagerly, the peninsula of Istria (Serbo-Croatian and Slovenian Istra), whose territory is now almost entirely included in Croatia, under the empire of Augustus was part of the Regio X, Venetia et Histria. After the fall of the Roman Empire, Istria was conquered by Odoacer, then by Theodoric and from 539 it passed under the control of Byzantium; at the beginning of the century 7 ° began the penetration of the Slavic populations. In 787 Charlemagne subdued a large part of the region, except for the centers of the west coast, which remained linked to Constantinople until the century. 10 °; the Franks also introduced the feudal system in Istria by subjecting the Slavs to serfs. In 1040 Istria became an autonomous brand of the Germanic empire, it was then granted (1077) to the patriarch of Aquileia, who ruled it until 1420 with the help of the landed aristocracy of German origin. In the struggle against the feudal nobility, the maritime cities organized themselves into free communes over which Venice extended its political influence from 1202 to 1331, until it conquered the peninsula after 1420 with the exclusion of the north-eastern area passed to the Habsburgs. Paleochristian basilicas (5th century) belong to the so-called Upper Adriatic type and are directly influenced by the monuments of Aquileia; these complexes are all flat terminated, without a projecting apse and with a semicircular subsellio in the presbytery, as for example. the cathedral of Pula, the ‘pre-Euphrasian’ basilica of Poreč (Poreč), that of Nesactium-Visazze (Nezakcij) and the ruins of a small building in the Brijuni islands. In Betiga (Betika), near Punta Barbariga, the church of S. Andrea, modest triloba foundation, which in the century. 6 ° was enlarged with the addition of a longitudinal body with three naves. Many basilicas retain part of the early Christian floor mosaics (eg Parenzo, Betiga); among the sacred furnishings stands the Samagher reliquary-box, dating back to the 16th century. 5th, formerly in Pola (Pula), now in Venice (Archaeological Museum). The Byzantine domination during the reign of Justinian (527-565) left monuments of considerable value in Istria: the Euphrasian cathedral of Poreč, almost entirely preserved, was built around 550, according to the scheme of the great Ravenna basilicas, and was equipped with a triconca martyrial chapel on the northern side and an atrium on the facade that served as a connection with the baptistery and the episcope (salutatorium), both from the mid 5th century. The marble capitals of the cathedral and atrium are products of Constantinopolitan workshops, while the mosaics, of high quality, are similar to those of S. Vitale in Ravenna. In Pula the archbishop of Ravenna Massimiano (546-556) erected the basilica of S. Maria Formosa, now in ruins, with two cruciform plan martyrias on either side of the apse, of which only one has preserved the domed roof and fragments of mosaic decoration. Contemporary to the Maximian foundation were the church of S. Caterina, located on a small island in front of Pola and, in the surrounding area, the churches of S. Michele in Monte and S. Clemente, destroyed in the nineteenth century and known through some drawings. The Istrian early medieval churches are mainly small in size and have a rectilinear layout with the apse obtained in the thickness of the wall; to this typology belong the basilica building of S. Fosca, not far from Peroi (Peroj), the biapsidal hall of S. Maria Minore, near Valle d’Istria (Bale), and the Santa Sofia of Docastelli (Dvigrad), with a single nave, which preserves fragments of Carolingian frescoes from the 9th century in the triapsidal choir. This particular apse shape had continuity of use in rural areas even in the Romanesque and early Gothic period, marking a specific regional phenomenon.
Other foundations of early medieval origin are the cathedral of St. Euphemia in Rovinj (Rovinj), from the 13th century. 6th, St. Elisha near Fazana (Fažane), also from the 13th century. 6 °, and S. Pietro in Selve, near Gallesano (Galižane). Among the numerous documents of early medieval liturgical furnishings, all fragmentary, the oldest are the hexagonal ciborium with the inscription of Bishop Maurizio (8th century), in the lapidary of the collegiate church of S. Pelagius in Cittanova (Novigrad), the pergula of the S. Sofia in Docastelli and the sarcophagus of the century. 9th of the parish church of S. Elia in Valle d’Istria. To the secc. The presbyterial gate of Loborika (Pola, Arheološki Muz. Istrie) and various stone pieces deposited in the cathedrals of Pola and Parenzo can be dated 9th and 10th; The sarcophagus of the church of S. Silvestro near Gallesano dates back to after the year 1000, bearing the name of the stonecutters Galibertus and Iohannes. 11 ° the Camaldolese abbey of S. Michele di Leme was built, with a single nave ending in a semicircular apse. A simple and at the same time monumental complex is constituted by the S. Martino in San Lorenzo del Pasenático (Lovreč), with three naves with semicircular apses (11th century); other Romanesque buildings with basilical forms are those of S. Giusto di Gallesano and S. Maria di Orsera (Vrsar). In the group made up of churches of the so-called Istrian type – with a single nave of reduced dimensions and a non-projecting apse -, the S. Elia in Valle d’Istria has as a variant a proportionate bell tower on the facade; Furthermore, the thirteenth-century heptagon of the Holy Trinity in Rovinj stands out for its originality. Few stone sculptures are preserved from the Romanesque period, often with a rustic model, such as for example. S. Giorgio in the parish church of the same name in Fianona (Plomin), the relief of two saints on a house in Poreč and the architectural decoration of the first town hall in Pola (1296 ca.); the wooden crucifixes of the century. 12 ° in Valle d’Istria, Gallesano, Gračišće and on the island of Susku, on the other hand, denounce a higher level of execution. 11 °, stylistically fall within the Ottonian current: the stoning of s. Stephen and the figure of a holy monk are, moreover, the only pictorial episodes still legible. Frescoes always of the century. 11th decorate the northern wall of the church of S. Martino in San Lorenzo del Pasenático, while the scene of the Ascension of Christ in S. Fosca near Peroi dates from the end of the same century. The Byzantine paintings of the chapel of S. Agata near Canfanaro (Kanfanara), with Christ in glory together with the group of apostles, are dated to the beginning of the century. 12 °, while the frescoes in the cemetery church of S. Gerolamo in Colmo (Hum), dating back to the 12th century. 12 ° -13 °, they appear dependent on the ways of the Upper Adriatic painting centered in Aquileia. The most interesting of the Istrian cycles, both for the wealth of testamentary episodes depicted and for the execution of a painted calendar, is kept in the parish church of Sanvincenti, a late thirteenth-century undertaking signed by the master Trivisan.