The prince (archon) that led the Serbs to the Balkans and received the protection of Heraclius (r. 610–641), known conventionally as the Unknown Archont, was an ancestor of Vlastimir.

[1] The Serbs at that time were organized into župe, a confederation of village communities (roughly the equivalent of a county),[2] headed by a local župan (a magistrate or governor).

[4] Emperor Constantine VII Porphyrogenitus (r. 913–959) mentions that the Serbian throne is inherited by the son, i.e., the first-born,[1] though on one occasion there is a triumvirate in his enumeration of monarchs.

[5][6] The DAI's account about the Serbian ethnic settlement and establishment of several future principalities by the 10th century is considered as highly disputable: Serbia (roughly the later province of Rascia, including Bosnia; part of Zagorje - "hinterlands"); and Pagania, Zachlumia, Travunia (including Kanalitai) and Dioclea (part of Pomorje - "maritime").

In 805, khan Krum conquered the Braničevci, Timočani and Obotrites, to the east of Serbia, banished their tribal chiefs, and replaced them with administrators appointed by the central government.

[19] In 818 during the rule of Omurtag (814–831), the Braničevci and Timočani together with other tribes of the frontiers, revolted and seceded from Bulgaria because of an administrative reform that had deprived them much of their local authority.

[20] The Timočani left the societas (association, alliance[21]) of the Bulgarian Empire, and sought, together with the Danubian Obotrites and Guduscani, protection from Holy Roman Emperor Louis the Pious (r. 813–840), and met him at his court at Herstal.

[21] The Timočani migrated into Frankish territory, somewhere in Lower Pannonia, and were last mentioned in 819, when they were persuaded by Ljudevit to join him in fighting the Franks.

[22][23] The Bulgarian state had a general policy of expansion in which they would first impose the payment of tribute on a neighboring people and the obligation of supplying military assistance in the form of an alliance (societas), leaving them internal self-government and local rulers, and when the need for this kind of relationship expired, they would terminate the self-government arrangement and impose direct and absolute power, integrating their neighbor fully into the Bulgarian political and cultural system.

[6][25] The Serbs most likely consolidated due to alarm at the advance of Bulgaria towards their borders—a rapid conquest of neighbouring Slavs[26][27]—in self-defence,[26][28] and possibly sought to cut off the Bulgarian expansion to the south (Macedonia).

[36] Vlastimir's intent to connect to the ruling house of Travunia shows, in context, that his reputation among the neighbouring Serbian archontes and župani was on the rise, as well as the political importance and military strength of Serbia.

[37] The elevation of Krajina's title (which meant the practical independence of Travunia) strongly suggests that Vlastimir was a Christian ruler who understood very well the monarchal ideology that developed in the early Middle Ages.

[33] Soon after 846, with the end of the thirty-year-truce, Malamir (or Presian) invaded the regions of the Struma and the Nestos, and Empress-Regent Theodora (r. 842–855, the wife of Theophilos) answered by attacking Northern Thrace.

The Christianization is evident in the tradition of theophoric names found in the next generation of Serbian monarchs (e.g., Petar Gojniković, Pavle Branović).

The following year, the Byzantine army, led by Michael III and caesar Bardas, recaptured Philippopolis (Plovdiv), the region of Zagora and the ports around the Gulf of Burgas on the Black Sea.

On July 11, 2006, A golden seal of Strojimir, dated to 855–896, was acquired by the Republic of Serbia at auction in Munich, Germany, for €20,000, beating a Bulgarian bid of €15,000 .

The seal is of Byzantine handcraft (from Athens, Thessaloniki or Constantinople), weighs 15.64 g, and has a patriarchal cross and a Greek inscription that reads: "Strojimir" and "God, Help Serbia".