This holy and glorious Serbian king and wonderful martyr of Christ, John Vladimir, grew up from pious and royal roots who ruled in the Serbian principalities of Zahumlje and Prevala (which was also called Diocletian, Duklja or Zeta). His grandfather was called Hvalimir and had three sons: Petrislav, Dragimir and Miroslav. Petrislav received Zeta (Duklja) into his administration, Dragimir Travunija (Trebinje) and Hlevna (Hum), and Miroslav Podgorje. But Miroslav had no children, and his state came into the power of Petrislav, who had his son, this blessed Vladimir, as his heir. And so Vladimir became king (in the second half of the tenth century) in Duklja and other parts of Illyria and Dalmatia, and his capital was at the church of the Most Pure Virgin Mary in the Krajina region (on the western side of Lake Skadar).

https://svetigora.com/kalendar-za-4-jun-5/