Although his brother Andrija Mirosavljević was entitled as heir of Miroslav, the Hum nobility chose Petar as Prince of Hum. Petar exiled Andrija and Miroslav's widow, Andrija fled to Rascia, to the court of Stefan Nemanjić. At the meantime, Petar fought successfully with neighbouring Bosnia and Croatia. Stefan Nemanjić sided with Andrija and went to war and secured Hum and Popovo field for Andrija sometime after his accession. Petar was defeated and crossed the Neretva, continuing to rule the west and north of the Neretva, which had before 1203 been briefly occupied by Andrew II of Hungary.
Stefan gave the titular and supreme rule of Hum to his son Radoslav, Andrija initially held the district of Popovo with the coastal lands of Hum, including Ston. By agreement, when Radoslav died, the lands were bound to Andrija.
Fine, John Van Antwerp (1994). The Late Medieval Balkans: A Critical Survey from the Late Twelfth Century to the Ottoman Conquest. Michigan: The University of Michigan Press. pp. 52–54. ISBN0472100793. 123 (ref name TLMB)