Orodes III, raised to the throne of the Parthian Empire around CE 4 by the magnates after the death of Phraates V of Parthia, is killed after a short reign "on account of his extreme cruelty" (Josephus).

After the assassination of Orodes III in about the year CE 6, the Parthians apply to Augustus for a new King from the house of Arsaces.

Augustus sends them Phraates V's brother Vonones I, the eldest son of Phraates IV.

Vonones I of Parthia, having been educated as a Roman, is despised by the Parthian nobility as a slave of the Romans.

Artabanus II, who is living among the Dahan nomads in the east of Parthia (and who seems to have been a non-Arsacid Parthian nobleman), is invited to the throne between CE 8 and 10 by those Parthian grandees who will not acknowledge Vonones I, who proves to have too tight a control over the budget.

However, when Artabanus attempts to consolidate his position (at which he is successful in most instances), he fails to do so in the regions where the Parthian provincial rulers hold sway.

The war between the two pretenders is long and doubtful; on a coin Vonones mentions a victory over Artabanus.

The coins of Vonones I date from 8 to 12 CE and bear the inscription "King Vonones, conqueror of Artabanus", commemorating a temporary victory over his rival.

Those of Artabanus II begin in the year 10.

At last Artabanus defeats his rival completely and occupies the Parthian capital, Ctesiphon.

Vonones, deposed by Artabanus II, flees to Armenia in about the year 12, where he is acknowledged as king, under the protection of the Romans.

The Middle East: 16–27 CE

Parthian Instability and Roman Intervention

The uneasy stability achieved by Rome's cautious diplomacy in the preceding era rapidly deteriorates, leading to further upheaval in Parthia. Vonones I, installed with Roman support, struggles to maintain his legitimacy amidst escalating resentment among the Parthian nobility due to his overtly Romanized manner and affiliations. By 16 CE, internal opposition compels Vonones to flee, first to Armenia and subsequently to Roman protection in Syria, where he lives under Roman custody.

Seizing upon this power vacuum, the Parthian aristocracy invites Artabanus II, ruler of Media Atropatene, to assume the Parthian throne. Artabanus II swiftly consolidates his position around 18 CE, adopting a distinctly anti-Roman stance. His assertiveness marks a new phase of Parthian resurgence, significantly shifting regional dynamics and prompting renewed Roman diplomatic and military attention.

Roman interests, deeply invested in the status of Armenia as a critical buffer state, become increasingly concerned by Artabanus's assertiveness, which threatens to destabilize the carefully maintained balance of power. Artabanus openly challenges Roman hegemony, maneuvering to install a pro-Parthian king in Armenia. Rome responds swiftly, deploying diplomatic envoys backed by the implicit threat of military intervention.

In 20 CE, the Roman general and future emperor Germanicus Caesar travels eastward to assert Roman interests, but his sudden death in Antioch in 19 CE delays decisive action, fueling suspicion and tension on both sides. Meanwhile, Artabanus's domestic policy of centralization provokes discontent among the powerful Parthian noble houses, fostering continued instability within the Parthian state.

The era concludes with Artabanus II temporarily consolidating power but presiding over an increasingly fragmented realm. Rome, for its part, continues to carefully monitor Parthian internal politics, ready to exploit weaknesses and preserve its strategic influence in Armenia and the broader Middle East. The ongoing rivalry between Rome and Parthia thus persists, characterized by diplomatic maneuvering, shifting alliances, and intermittent threats of war.

Artabanus II had been raised to the throne in about CE 10 by those Parthian grandees who would not acknowledge Vonones I, whom the Roman Emperor Augustus had sent from Rome (where he lived as hostage), as successor of his father late Phraates IV.

The war between the two pretenders is long and doubtful; on a coin Vonones mentions a victory over Artabanus.

Artabanus in CE 12 at last defeated his rival completely and occupied the Parthian capital Ctesiphon.

Vononeshad fled to Armenia, where he was acknowledged as king, under the protection of the Romans.

But when Artabanus, demanding his deposition, invaded Armenia, Vonones fled to Syria, and the emperor Tiberius thought it prudent to support him no longer.

As Augustus does not wish to begin a war with the Parthians, he removes Vonones I into Syria, where he is kept in custody, though in a kingly style.

Tiberius' nephew and heir Germanicus, whom he sends to the East, concludes a treaty with Artabanus, in which he is recognized as king and friend of the Romans.

Germanicus organizes Cappadocia and Commagene into provinces.

During a sightseeing trip to Egypt (not a regular province, but the personal property of the Emperor) he seems to have unwittingly usurped several imperial prerogatives.

The Romans finally succeed in restoring control of Armenia, reducing it to the status of troublesome client state, ruled from CE 18 by Zeno, the son of the king of Pontus.

The Middle East: 28–39 CE

Parthian Struggles and Roman Diplomacy

During the period from 28 to 39 CE, tensions within the Parthian Empire continue to challenge regional stability. Artabanus II, initially successful in consolidating authority, now faces intense internal opposition driven by powerful Parthian aristocratic factions increasingly dissatisfied with his centralization efforts and assertive foreign policy.

In 35 CE, discontent among these elites culminates in open rebellion, prompting some Parthian nobles to seek assistance from Rome. Seizing this diplomatic opportunity, Roman authorities under Emperor Tiberius actively encourage instability by supporting rival claimants to the Parthian throne, notably backing Tiridates III, a Parthian prince with significant Roman connections. Roman support for Tiridates culminates in his temporary installation as a rival king in 36 CE, forcing Artabanus II into exile among eastern nomadic tribes.

However, Artabanus swiftly regroups, leveraging tribal alliances to mount a successful counteroffensive. By 37 CE, he regains control over Ctesiphon, expelling Tiridates and restoring his authority. Understanding the limits of Roman intervention, Emperor Caligula, who succeeds Tiberius in 37 CE, chooses not to pursue aggressive confrontation, instead accepting Artabanus’s reinstatement and renewing diplomatic relations.

Simultaneously, Rome carefully manages the delicate political situation in Armenia, maintaining the kingdom as a crucial buffer state and preserving influence through client kings and strategic diplomacy. The Roman-Parthian rivalry thus remains largely unresolved, characterized by intermittent proxy conflicts, strategic maneuvering, and cautious diplomacy, shaping the region’s ongoing balance of power.

The Middle East: 40–51 CE

Parthian Rivalries and Roman Regional Strategies

Between 40 and 51 CE, the Parthian Empire again descends into internal strife, exacerbated by external Roman intervention. In 40 CE, Emperor Caligula dispatches forces to strengthen Rome's grip over client states and indirectly assert influence over Armenia. His assassination in 41 CE and the accession of Claudius usher in a pragmatic shift in Roman eastern policy, characterized by strategic restraint and careful diplomacy rather than overt military campaigns.

Parthia’s Artabanus II dies around 38 CE, leading to further instability. His successor, Vardanes I, ascends the throne but faces immediate opposition from his brother, Gotarzes II, sparking a destructive civil war. Throughout the early 40s CE, the two brothers engage in intermittent conflicts, with Vardanes briefly securing dominance before his assassination in 45 CE. Gotarzes II regains power but continues to contend with widespread aristocratic unrest and regional rebellions.

Seizing upon Parthian disarray, Rome employs diplomatic maneuvers, indirectly supporting rival claimants to maintain Parthian internal divisions while preserving a manageable frontier. In 49 CE, the Parthian nobility invites Meherdates, a hostage prince raised in Rome, to challenge Gotarzes. Meherdates, however, suffers defeat, securing Gotarzes' tenuous rule until his death in 51 CE.

Amid these conflicts, Rome consistently focuses its influence on Armenia, which remains pivotal to regional stability. The kingdom alternates between pro-Roman and pro-Parthian rulers, reflecting the ongoing, careful diplomatic tug-of-war. Thus, by 51 CE, the Middle East continues as a theater of indirect conflict, shaped by Parthian dynastic rivalries and Rome’s strategic emphasis on diplomatic intervention rather than outright conquest.