…Roman refugees fleeing the Slav and Avar sack of Epidaurus establish Rausa, or Ragusium (modern Dubrovnik, Italian Ragusa), just to the northwest.

A colony of Slavs soon joins the Romans there.

No contemporary written records about the migration of Croats have been preserved, especially not about the events as a whole and from the area itself.

Instead, historians rely on records written several centuries after the facts, and even those records may be based on oral tradition.

The Croats came as a Slavic tribe, coming into the Balkans from an area in and around today's Poland or western Ukraine.

Many modern scholars believe that the early Croat people were nomadic Iranian-speaking Alans who ruled over Slavic agricultural populations.

It is unclear whether the Alans contributed much more than a ruling caste or a class of warriors; the evidence on their contribution is mainly philological and etymological.

The book De Administrando Imperio, written in the tenth century, is the most referenced source on the migration of Slavic peoples into southeastern Europe.

It states three different variations of the events.

First, that Croats migrated around or before year 600 from White Croatia, the region that is now (roughly) Galicia, to the province of Dalmatia ruled by the Roman Empire, led by a group of five brothers, Kloukas, Lobelos, Kosentzis, Mouchlo and Chrobatos, and their two sisters, Touga and Bouga.

The second, possibly around year 620, when the Croats are invited by the Emperor Heraclius to counter the Avar threat on the Empire.

Third, where the Croats weren't actually invited by Heraclius, but instead defeat the Avars and settle on their own accord after migrating from an area near today's Silesia.

This record is supported by Historia Salonitana, the thirteenth-century writings of one Thomas the Archdeacon.

Archdeacon Thomas, as well as the twelfth-century Chronicle of the Priest of Duklja from the, state that the Croats remained after the Goths (under a leader referred to as "Totila") had occupied and pillaged the Roman province of Dalmatia.

The Chronicle speaks of a Gothic invasion (under a leader referred to as "Svevlad", followed by his descendants "Selimir" and "Ostroilo").

Leo, failing in his efforts to restore imperial authority in the west, places Illyria, Calabria, and Sicily—all currently controlled by the pope—under the jurisdiction of the patriarch of Constantinople, thus permitting a unified program of re-Christianization of much of this region. (The Albanian lands for centuries hereafter will become an arena for the ecclesiastical struggle between Rome and Constantinople.

Most Albanians living in the southern and central regions, the majority, will become Orthodox, while …

Koper, having arisen from an ancient settlement built on an island in the southeastern part of the Gulf of Koper in the northern Adriatic, was known as Aegida (Goat Town) in Ancient Greek, later becoming known by the Latin names of Capris (Greek Copros), Caprea, Capre, or Caprista, from which the modern Slovenian name stems.

Roman citizens of nearby Tergeste (modern Trieste) had fled to Capris in 568 due to an invasion of the Lombards.

The town, renamed Justinopolis in honor of the emperor Justinian II, was later under both Lombard and Frankish rule and was briefly occupied by Avars in the eighth century.

Koper has been the seat of a diocese since the eighth century, possibly even since the sixth century.

Trade between Koper and Venice has been recorded since 932.

Koper is on the German side in the war between Venice and the Holy Roman Empire, and as a result is granted town rights by Emperor Conrad II in 1035.

Ragusa (centered upon modern Dubrovnik), victimized by Dalmatian Muslim pirates, had joined Constantinople in 1030 in a series of naval wars against the raiders.

After their combined fleet crushes the pirates in the Adriatic in 1032, the imperial warships, manned chiefly by Scandinavian mercenaries, patrol the Mediterranean, winning several encounters over Muslim pirates and ravaging parts of North Africa's Muslim-controlled coast.

The Dalmatian city states, having gradually lost all protection by Constantinople and being unable to unite in a defensive league hindered by internal dissension, had had to turn to either Venice or Hungary for support.

Each of the two political factions had had support within the Dalmatian city states, based mostly on economic reasons.

The Venetians, to whom the Dalmatians are already bound by language and culture, could afford to concede liberal terms as their main goal is to prevent the development of any dangerous political or commercial competitor on the eastern Adriatic.

The seafaring community in Dalmatia looks to Venice as mistress of the Adriatic.

In return for protection, the cities have often furnished a contingent to the army or navy of their suzerain, and sometimes paid tribute either in money or in kind.

Arbe (Rab), for example, annually paid ten pounds of silk or five pounds of gold to Venice.

Hungary, on the other hand, had defeated the last Croat king in 1097 and forced Croatian noblemen into a personal union with the treaty of 1102.

King Coloman in 1102–1105 had proceeded to conquer Dalmatia, and in 1108 control passes to Hungary.

The farmers and the merchants who trade in the interior favor Hungary as their most powerful neighbor on land that affirms their municipal privileges.

Subject to the royal assent they might elect their own chief magistrate, bishop and judges.

Their Roman law remains valid.

They are even permitted to conclude separate alliances.

No alien, not even a Hungarian, can reside in a city where he is unwelcome; and the man who dislikes Hungarian dominion can emigrate with all his household and property.

In lieu of tribute, the revenue from customs is in some cases shared equally by the king, chief magistrate, bishop and municipality. (As the age progresses, these rights and the analogous privileges granted by Venice will, however, too frequently be infringed. Hungarian garrisons will be quartered on unwilling towns, while Venice will interfere with trade, the appointment of bishops, or the tenure of communal domains. Consequently, the Dalmatians are to remain loyal only while it suits their interests, and insurrections will occur frequently.)

Venice, with aid from the Norman kingdom of Sicily in 1172, seizes Ragusa and …

The joining of the Croatian and Hungarian crowns had automatically made Hungary and Venice rivals for domination of Dalmatia.

Hungary seeks access to the sea, while Venice wishes to secure its trade routes to the eastern Mediterranean and to use Dalmatian timber for shipbuilding.

Between 1115 and 1420, the two powers will wage twenty-one wars for control of the region, and Dalmatian cities will change hands repeatedly.

Serbia and Bosnia also compete for Dalmatia.

Serbia seizes the coast south of the Gulf of Kotor on the southern Adriatic around 1196 and holds it for one hundred and fifty years; Bosnia dominates central Dalmatia during the late fourteenth century.

Dalmatian cities struggle to remain autonomous by playing off one power against the others.

Most successful in this strategy is Ragusa (today Dubrovnik), whose riches and influence at times rival those of Venice.

In the fourteenth century, Ragusa becomes the first Christian power to establish treaty relations with the Ottoman Empire, which is at this time advancing across the Balkans.

Ragusa will prosper by mediating between Europe and the new Ottoman provinces in Europe and by exporting precious metals, raw materials, agricultural goods, and slaves.

After centuries as the only free South Slav political entity, the city will wane in power following a severe earthquake in 1667.

…Dubrovnik/Ragusa—continue to regain their self-governing status, whether possessed by Hungary or its regional rival, Venice.

…the Republic of Dubrovnik (Ragusa), formerly under Serbian control, which in 1358 accepts Hungarian sovereignty.

… Dubrovnik, or Ragusa, whose riches and influence at times rival those of Venice.

The Rebublic of Ragusa in the fourteenth centur becomes the first Christian power to establish treaty relations with the Ottoman Empire, which is now advancing across the Balkans.

Dubrovnik prospers by mediating between Europe and the new Ottoman provinces in Europe, and by exporting precious metals, raw materials, agricultural goods, and slaves.