Research Notes:

Tigranes IV succeeded his father Tigranes III before 6 BCE, [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 abridged that it is obscure. However, he records that the Armenians were becoming estranged from the Romans after the death of Tigranes III, [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, [Cassius Dio, Roman History 55.10.18.] causing some diplomatic exchanges between the Parthian king Phraataces and the emperor Augustus. [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). [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"; [Tacitus, Annals 2.4.] Cassius Dio believes that the pretender succumbed to an illness. [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". [Cassius Dio, Roman History 55.10a.5.].... ¹

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In 8 BC, the Armenians installed Tigranes IV as King as the successor to his father. In accordance with Oriental custom or Hellenistic custom, Tigranes IV married his sister Erato in order to preserve the purity of the Artaxiad Royal blood line. Erato through marriage to her brother, became Queen and his Queen consort. From their sibling union at an unknown date, Erato bore Tigranes IV an unnamed daughter who later married King Pharasmanes I of Iberia who ruled from 1 until 58, and by whom he had three sons: Mithridates I of Iberia, Rhadamistus and Amazaspus (Amazasp) who is known from a Greek inscription found in Rome.

Although Tigranes IV and Erato were Roman Client Monarchs governing Armenia, they were both anti Roman and were not the choices of the Roman emperor Augustus for the Armenian throne, as their dual rule did not have Roman approval and they leaned towards Parthia for support.

Rome and Parthia competed with one another for their protégés to have influence and govern Armenia. Roman Historian of the 4th century, Sextus Rufus informs us that anti-Roman sentiment was building in Armenia during the reign of Tigranes IV and Erato. Rufus also emphasizes that the Kingdom of Armenia was very strong during this period.

The dispossessed and the discontent of the ruling Artaxiad monarchs and their subjects towards Ancient Rome had instigated war with the aid of King Phraates V of Parthia. To avoid a full-scale war with Rome, Phraates V soon ceased his support to the Armenian ruling Monarchs. This lead Tigranes IV and Erato, acknowledging Roman suzerainty; sending their good wishes and submission to Rome. Augustus receiving their submission to Rome and good wishes, allowed them to remain in power....

Sometime about 1 AD Tigranes IV was killed in battle, perhaps ending an internal Armenian revolt of those who were infuriated by the royal couple becoming allies to Rome. The war and the chaos that occurred afterwards, Erato abdicated her throne and ended her rule over Armenia.... ²