Although Alexander's expedition into the Georgian lands is entirely fictional, Georgian and Classical evidence suggests that the kings of Iberia cultivated close relations with the Seleucid Empire, a Hellenistic successor to Alexander’s short-lived empire centered on Syria, and at times recognized its suzerainty, probably aiding, as Professor Cyril Toumanoff has implied, their overlords in holding in check the Orontid Dynasty of neighboring Armenia.
Parnavaz is supposed by Toumanoff to have ruled from 299 to 234 BC. His son, Saurmag (r. 234-159 BC), is reported to have died without a male heir, and the dynasty survived in the female line through the marriage of Saurmag’s daughter to Mirian (I) (r. 159-109 BC), of the Nimrodids. The Nimrodids, in Georgian Nebrot'iani (ნებროთიანი), which means the "race of Nimrod", is not a dynastic name but the term applied by the medieval Georgian annalists to the ancient Iranians. Hence, the dynasty, although in the female line only, continues to be called by the chronicles as P’arnavaziani ("Second Pharnabazid" as suggested by Toumanoff).
The dynasty, in the person of Mirian's son, P’arnajom (r. 109-90 BC), was dispossessed of the crown by a branch of the Armenian Artaxiads whose ascendancy in Iberia lasted from 90 to 30 BC when the Pharnabazids were able to resume the throne. By that time, the South Caucasus had been brought under Roman hegemony. However, Iberia succeeded in detaching itself from the Roman dominion in the last decade of the 1st century BC and emerged as a more powerful state in the 1st century AD. Pharasmanes I of Iberia (r. AD 1-58) energetically interfered in the affairs of Armenia which was then a bone of contention between Rome and Parthia and installed his brother, Mithridates (AD 35-51), on the throne of Armenia. In 51, however, Pharasmanes instigated his son, Rhadamistus, to remove Mithridates and occupy the Armenian throne, only to be expelled from his kingdom in 55. Pharasmanes's successor, Mihrdat I (58-106) forged an alliance with Rome to defend the Iberian frontiers from Alans, nomads from the north. A stone inscription discovered at Mtskheta, capital of Iberia, speaks of Mihrdat as "the friend of the Caesars" and the king "of the Roman-loving Iberians." In 75, the Roman Emperor Vespasian helped the king of Iberia to fortify the acropolis of Armazi.
Once the scions of Parthian Arsacids had consolidated their hold over Armenia in the second century AD, their branch replaced the Pharnabazids in Iberia. According to the Georgian chronicles, this happened when the nobles staged a revolt against Amazaspus (II) (r. 185-189) and with help of the king of Armenia, probably Vologases II (r. 180-191), who is reported to have been married to Amazasp’s sister, deposed and killed their monarch. Vologases installed his son and Amazasp’s nephew, Rev (I) (r. 189-216) on the throne of Iberia, inaugurating the local Arsacid dynasty.