Arsaces IV appears to have been the son of Arsaces II, who became king of the Parni in Parthia after Arsaces III Phriapatius: In these years, the Parni shook of the Seleucid yoke, benefitting from the problems in the Seleucid Empire that had been caused by the defeat of Antiochus III the Great against the Romans in the Syrian War (192-188).
As king, Arsaces IV may have continued Phriapatius' policies, but he was soon replaced by another king, Phraates I, who was to rule from 168 until 165, and was in turn succeeded by Mithradates I the Great (r.165-132). Both men were sons of Phriapatius.
The chronology of the Arsacid kings of the Parthian Empire is less well-understood than, for example, the sequence of Seleucid and Ptolemaic kings or the emperors of Rome. This information is based on the researches by G.R.F. Assar, as published in "Iran under the Arsakids, 247 BC – AD 224/227" in: Numismatic Art of Persia (2011).