Tigranes IV succeeded his father Tigranes III before 6 BCE,note[Cassius Dio, Roman History 55.9.9.] perhaps in 8 BCE. Our main source about his reign is the Greco-Roman historian Cassius Dio, whose account is at this point so abbridged that it is obscure. However, he records that the Armenians were becoming estranged from the Romans after the death of Tigranes III,note[Cassius Dio, Roman History 55.9.4.] which suggests a pro-Parthian policy. Indeed, the Armenian kingdom was at a later stage considered to be in a state of revolt,note[Cassius Dio, Roman History 55.10.18.] causing some diplomatic exchanges between the Parthian king Phraataces and the emperor Augustus.note[Cassius Dio, Roman History 55.10.18.]
When no solution was achieved, Augustus sent a pretender to the east, whose name was Artavasdes or Artabazus (two ways of spelling the same name).note[Cassius Dio, Roman History 55.10.20.] This was a descendant of a former Armenian king, Artavasdes II, who had been taken captive in 34 BCE by Mark Antony. Ever since, several relatives had been living in Rome. To strengthen his claim to the throne, he married Erato, his sister.
The Roman historian Tacitus says that this Artavasdes "was shaken off, not without a measure of discredit to Roman arms";note[Tacitus, Annals 2.4.] Cassius Dio believes that the pretender succumbed to an illness.note[Cassius Dio, Roman History 55.10.20.] Not much later, in the year 2 CE, Tigranes IV died as well: according to Dio, he "perished in a war with barbarians".note[Cassius Dio, Roman History 55.10a.5.]
In the meantime, Augustus' grandson Gaius Caesar had arrived in the east, acting with the powers of a consul.note[Cassius Dio, Roman History 55.10a.4.] (Among the officers that escorted the him were Sulpicius Quirinius, the historian Velleius Paterculus, Marcus Lollius, and Seianus, the future praetorian prefect.) In 1 CE, the Roman prince and the Parthian king Phraataces had met on an island in the Euphrates, and it was clear that the Parthians would not intervene in Armenia any more.
Learning that Augustus' candidate Artavasdes was dead and that the pro-Parthian king Tigranes IV was killed in action, Gaius selected Ariobarzanes, a former king of Media Atropatene who had been dethroned by the Parthians, as new king in Armenia. His reign, however, was to be brief.