Roman naval fleets.
From the early days of Roman rule, Zadar gained its Roman urban character and developed into one of the most flourishing centres on the eastern Adriatic coast, a state of affairs which lasted for several hundred years. The town was organised according to the typical Roman street system with a rectangular street plan, a forum, thermae, a sewage and water supply system that came from lake Vrana, by way of a 40 km long aqueduct. It did not play a significant role in the Roman administration of Dalmatia, although the archaeological finds tell us about a significant growth of economy and culture.
The new religion Christianity did not bypass the Roman province of Dalmatia. Already by the end of the 3rd century Zadar had its own bishop and founding of the Zadar Christian community took place; a new religious centre was built north of the forum together with a basilica and a baptistery, as well as other ecclesiastical buildings. According to some estimates, in the 4th century it had probably around ten thousand citizens, including the population from its Ager, the nearby islands and hinterland, an admixture of the indigenous Liburnians and Roman colonists.
Early Middle Ages
During the Migration Period and the Barbarian invasions, Zadar underwent a stagnation. In 441 and 447 Dalmatia was ravaged by the Huns, after the fall of the Western Roman Empire, in 481 Dalmatia became part of the Ostrogothic kingdom, which, besides Italy, already included the more northerly parts of Illyricum, i.e. Pannonia and Noricum.
In the 5th century, under the rule of the Ostrogothic Kingdom, Zadar became poor with many civic buildings turning into ruins due to its advanced age. About the same time (6th century) it was hit by an earthquake, which destroyed entire complexes of monumental Roman architecture, whose parts would later serve as material for building houses. This caused a loss of population and created demographic
