Croatia also waged battles with the Bulgarian Empire (founded c. 681; Bulgar-Croatian relations improved greatly afterwards) and with the Arabs; it also sought to extend its control over important coastal city-states under the rule of Byzantium.

[10] Within the area of the Roman province of Dalmatia, various tribal groupings, which were called sclaviniae by the Byzantines, were settled along the Adriatic coast.

[11] Several coastal Dalmatian city-states were under the rule of the Byzantines, including Split, Zadar, Kotor and Dubrovnik, as well as islands of Hvar and Krk.

[12] To the south Croatia bordered with the land of the Narentines, which stretched from the rivers Cetina to Neretva, and had the islands of Brač, Hvar, Korčula, Mljet, Vis and Lastovo in its possession.

[19] Although the Byzantine Empire managed to reconquest the territory (albeit the Plague of Justinian and Late Antique Little Ice Age),[20] since the mid-6th century followed even more devastating intrusions and migrations of the early Slavs.

[30][31] By the early 9th century, Croatia emerged as a political entity with a duke as head of the state, territorially in the basins of the rivers Cetina, Krka and Zrmanja.

Their land was divided in eleven zupanias, which are: Hlebiana, Tzenzena, Emota, Pleba, Pesenta, Parathalassia, Brebere, Nona, Tnena, Sidraga, Nina, and their ban has Kribasan, Litzan, Goutzeska.The evidence for the 7th century arrival of new Slavic(-Croatian) population are cremation burials, Prague culture pottery, fibulae and other artifacts found near them, which are atypical for a Roman and Christian population at the time,[33][34][35][36][37][38][39] as well destruction of inhabitations and churches, and changes of native's lifestyle.

[47] Croats from the late-8th and in the 9th century have high concentration of Carolingian-Viking swords (over 24,[48] mostly of K-type but also 1-type and H-type,[49][50] post-Carolingian emerge R-type and X-type[51][52]), and other war equpiment (including a long knife, long spear, and arrows, as well boots with spurs, belt trappings and else of Carolingian influence),[53] some considered as evidence of Croatian participation in the Frankish-Avar Wars in the late 8th and early 9th century (although Frankish sources do not mention Croatian ethnonym between early 7th and late 9th century[54]), and being part of the Central-European and Carolingian political and cultural world of influence at least since duke Borna (c. 810–821).

[57] They are neither evidence of a late 8th-early 9th century migration of Croats, as some scholars have argued, but as Frankish gifts of loyalty,[58] were influential to the consolidation of the Croatian elite identity and ethnogenesis at the time.

[62] Recent archaeological findings from Brekinjova Kosa at Bojna near Glina in Lower Pannonia, including rich burial (golden spurs with mounting set, pendant with rock crystal, gold coin of Constantine V, clothing woven with gold threads) belonging to a local duke at Bojna, which have very similar analogies in Biskupija near Knin and Morpolača near Stankovci in Dalmatia,[63] indicate it belonged to the Croats who spread control to the area around Sisak.

[65] Simpler jewellery of silver and bronze are S-type (typical of Sclaveni) and pseudo-S-type earrings, omega-type and star-shaped pendants of Byzantine origin, and many rings and necklaces.

[65] Rare containers made of antlers and engraved with iconography (two horned animals facing the tree of life between them) were also found only in Western Pannonia (Sopron and Zalavar, Hungary).

[67] Several archaeological findings and inscriptions dating to the late 8th and first half of the 9th century in the territory of early medieval Croatia show missionary activity of the Patriarchate of Aquileia.

In the 790s, Duke Vojnomir of Pannonia accepted the Frankish overlordship, whose land the Franks placed under the March of Friuli and tried to extend their rule over the Croatians of Dalmatia.

By that treaty the Byzantines retained control of the coastal cities and islands in Dalmatia, while acknowledging Frankish rule over Istria and the Dalmatian hinterland.

Because of this, a large army from Francia marched against them, and after they had fought one another for seven years, at last, and with hardship, the Croats managed to prevail and killed all the Franks and their archon, called Kotzil".

Along with the Narentines, who were still pagan at the time and occupied the territory of the river Neretva mouth, they were active in the Adriatic Sea and made shipping and traveling in the area hazardous, especially for Venice.

[88] Therefore, in 839 the Venetians under Doge Pietro Tradonico attacked the eastern coast of the Adriatic, including Croatia, but during the assault they signed peace with their ruler, princeps Mislav (Latin: principe Muisclavo), who ruled from Klis near Split.

The Doge also attacked Narentine islands, but failed to defeat them and made peace with their leader, who is mentioned as count Drosaico by the chronicler John the Deacon.

[90] Duke Mislav was succeeded around 845 by Trpimir I, who continued the formal legacy of being the vassal of the Frankish king Lothair I (840–855), although he managed to strengthen his personal rule in Croatia.

[97] In 864 Duke Domagoj, founder of the House of Domagojević, usurped the throne after the death of Trpimir and forced his sons, including Zdeslav, to flee to Constantinople.

The pirates attacked Christian sailors, including a ship with papal legates returning from the Eighth Catholic Ecumenical Council,[98] thus forcing the Pope to intervene by asking Domagoj to stop piracy, but his efforts were of no avail.

The Pope replied to his requests, praising his initiative and in 879 the Duchy under Branimir, now free of Frankish suzerainty, received papal recognition as a state.

[102] Muncimir (also called Mutimir), the youngest son of Trpimir, came to throne after the death of Branimir (c. 892), which marked the return of the House of Trpimirović to power.

[108] According to De Administrando Imperio, Croatia at the time had 100,000 infantrymen and 60,000 horsemen, 80 large ships and 100 smaller vessels,[91] but these numbers are viewed as a clear exaggeration and an overemphasis of the Croatian forces.

In a note preceding the text of the Council conclusions in Split in 925 it is written that Tomislav is the king "in the province of the Croats and in the Dalmatian regions" (in prouintia Croatorum et Dalmatiarum finibus Tamisclao rege).