Much of Bosnia is taken over after the death of Tomislav in 928 by a Serb princedom that acknowledges the sovereignty of Constantinople.

The first recorded mention of Bosnia is written during this period by the the Greek emperor Constantine VII Porphyrogenitus, whose writings are one of the best sources of information on the Greek empire and neighboring areas.

Describing “Bosona” as a district in “baptized Serbia,” the district he refers to is an area much smaller than modern Bosnia and centered on the Bosna River.

Soon after Constantine writes those words, most of the modern territory of Bosnia reverts to Croatian rule.

The Magyars, or Hungarians, take Bosnia around 1000.

Constantinople’s rule over Bosnia had fallen away after the death of the emperor Manuel I Komnenos in 1180, but government by Croatia or Hungary had not been restored.

During the reign of the native Bosnian Kulin, ruler of Bosnia from about 1180 as ban, or viceroy, of the king of Hungary, Hungarian influence dwindles and Bosnia functions as a largely independent state.

The country also enjoys a period of peace and relative prosperity through increased trade.

At this time, the term Bosnia encompasses roughly the lands of Vrhbosna, Usora (region), Soli, the Donji Kraji and Rama, which is approximately geographical Bosnia.

Most of the Bosnian territory (excluding modern Herzegovina) has been Roman Catholic following the division between Roman Catholic and Eastern Orthodox Christianity, but during the long period of isolation from Rome the Bosnian church has fallen into de facto schism, electing its own leaders from among the heads of the monastic houses.

A combination of poor theological training, lax observances, and Eastern Orthodox practices has led to frequent complaints from neighboring areas, beginning in the 1190s, that the Bosnian church is infected with heresy.

From the 1190s, a number of regional rulers and Roman Catholic church leaders, most of whom have ulterior political motives, accuse Kulin of sheltering Bogomil heretics in his domain.

Some even claim that the Bosnians have adopted Bogomilism on a large scale.

Kulin responds in 1203 by calling a special church council at Bolino Polje, at which Bosnian church leaders affirm the authority of the pope and commits themselves to a series of reforms correcting lax religious practices; in addition, however, they promise not to shelter heretics in their monasteries.

Stephen Kotroman, a vassal of the Hungarian king, had from 1287 to 1316 ruled a portion of Bosnia.

His son Stephen (Stjepan) Kotromanic in 1322 becomes the independent lord of all Bosnia.

… the land of Hum (later called Herzegovina) to Bosnian ban Stephen (Stjepan) Kotromanic, who, extending his domain southward, incorporates also the Adriatic coastline between Split and the Neretva River.

… the short-lived Bosnian state of Tvrtko Kotromanic, who rules from 1353 as Bosnian ban (provincial lord, subservient to the king of Hungary; Tvrtko in 1363 commences war with King Louis of Hungary, but afterward Louis helps him regain power following a revolution in Bosnia); and …

Bosnia's ban, the energetic Tvrtko Kotromanic, is challenged by Hungarian aggression and internal uprisings, but manages to establish firm control over a reduced Bosnia by 1370.

The energetic Stephen Tvrtko, taking advantage of internal crises among traditional Bosnian rivals Serbia and Hungary, has recovered Bosnia's lost territory, extended his lands along the Adriatic coast and into Serbia, and, as the Nemanjic dynasty had expired in 1371, in 1377 crowns himself “king of the Serbs, of Bosnia, and of the coast,” trumpeting his alleged Nemanja heritage; he will eventually add to his title Dalmatia and Croatia as well.

Whether his suzerain, Louis of Hungary, had approved Tvrtko's coronation cannot be decided.

Rival nobles and religious groups vie to gain control of Bosnia in 1391 after the death of Tvrtko; …