In 331 BC, during the
Battle of Gaugamela between the
Achaemenid ruler
Darius III and
Alexander the Great,
Medes,
Albans,
Sakasens,
Cadusians fought alongside the army of the Achaemenid
Great King in the army of Atropates. After this war, which resulted in the victory of Alexander the Great and the fall of the Achaemenid Empire, Atropates expressed his loyalty to Alexander. In 328-327 BC, Alexander appointed him governor of Media. Following the death of Alexander the Great in 323 BC, the Macedonian's conquests were divided amongst the
diadochi at the
Partition of Babylon. The former Achaemenid satrapy of
Media was divided into two states: The greater (southern) part –
Media Magna was assigned to
Peithon, one of Alexander's bodyguards. The smaller (northern) region, which had been the sub-satrapy of
Matiene, became
Media Atropatene under
Atropates, the former Achaemenid governor of all Media, who had by then become father-in-law of
Perdiccas, regent of Alexander's designated successor. Shortly thereafter, Atropates refused to pay allegiance to
Seleucus, and made Media Atropatene an independent kingdom. In 223 BCE,
Antiochus III came to power in the
Seleucid Empire, one of the
Hellenistic states that had emerged following the death of Alexander. Antiochus attacked Atropatene, resulting in a victory. by king Artaxias I (190—160 B.C.) Consequently, the king of Atropatene,
Artabazanes, accepted the ascendency of Seleucids and became dependent on it; on the other hand, interior independence was preserved. At the same time, the Roman Empire came into sight in the Mediterranean basin and was trying to spread its power in the East, and in 190 B.C., its army met and defeated the Seleucids' army in the
battle of Magnesia.
Parthia and Atropatene subsequently considered Rome a threat to their independence and allied themselves in the struggle against Rome. After the battle between Rome and the
Parthians in 38 BC, the Romans won and the Roman general Antony attacked Fraaspa (36 BC), one of the central cities of Atropatene. The city was surrounded by strong defenses. After a long blockade, Antony receded, losing approximately thirty-five thousand soldiers. In the face of Parthian attempts to annex Atropatene, Atropatene began to draw closer to Rome, thus, Ariobarzan II, who came to power in Atropatene in 20 BC, lived in Rome for about ten years. The dynasty Atropates founded would rule the kingdom for several centuries, first independently, then as vassals of the
Arsacids (who called it 'Aturpatakan'). It was later supplanted by a line of the
Arsacids. During the late Parthian era, after Pharasmanes II of Iberia devastated Media Atropatene and forced Parthia to pay tribute in 134-135 AD, empire was significantly damaged, resulting in the weakening of hold over western and northern Iran. The
Iranologist Touraj Daryaee argues that the reign of the Parthian monarch
Vologases V () was "the turning point in Arsacid history, in that the dynasty lost much of its prestige." The people of Atropatene (both nobility and peasantry) allied themselves with the Persian
Sasanian prince
Ardashir I () during his wars against Vologases V's son and second successor
Artabanus IV (). In 226, Atropatene submitted with little resistance to Ardashir I after he had defeated and killed Artabanus IV at the
Battle of Hormozdgan. Ardashir I and his son and heir
Shapur I () are depicted in a
rock relief near
Salmas, possibly a testimonial to the Sasanian conquest of Atropatene. The nobility of Atropatene most likely allied themselves the Sasanians due to a desire for a strong state capable of maintaining order. The priesthood, who may have felt alienated by the easy-going Arsacids, probably also supported the Sasanian family, due to its association with
Zoroastrianism. == Zoroastrianism ==