| Year | Date | Event |
| 800 | | Radoslav of Serbia, was a Serbian Prince who ruled over the Serbs from 800 to 822, he succeeded his father Višeslav, who was the first ruler known by name of the early medieval Principality of Serbia. His son Prosigoj succeeded him in ca. 822 |
| 822 | | Ljudevit Posavski, Prince of Pannonian Slavs, becomes a Prince of Serbs in Pagania's city of Srb as the Franks approach the Serbian lands. This Serbo-Croatian defence union expires in 823. |
| 825 | | In the Principality of Serbia, the House of Višeslavić-Vlastimirović strengthens the state against its immediate neighbors the Frankish Empire, the First Bulgarian Empire and the Byzantine Empire. Vlastimir of Serbia repels Bulgarian attacks led by Khan Boris. |
| 863 | | Missionaries Sts. Cyrill and Methodius are sent to Serbia on the order of Byzantine emperor Michael the III to fully convert Serbs to christianity. |
| 900 | | Višeslav's son, or grandson, ruled during the uprisings of Ljudevit Posavski against the Franks in 819–822. According to the Royal Frankish Annals, in 822, Ljudevit went from his seat in Sisak to the Serbs somewhere in western Balkans – the Serbs are mentioned as reportedly holding the great/large part of Dalmatia. |
| 900 | | The Magyars settle in Slavic Pannonia effectively splitting the South Slavs from the West Slavs. Occasional clashes with Byzantine, Bulgarian and Serbian forces in frontier regions. |