The empires of Persia

The Iranian plateau was the heartland of three great empires whose territory stretched from ancient centras of civilization in Mesopotamia to India. For more than a millennium, the Persian empire was goverened successively by the Achaemenid, Arsacid and Sasanid ruling families, and offered a constant challenge to the Mediterannean lands to the west.

The downfall of the Assyrian empire around 612 BC was brought about by the Babylonians and the Medes, a loose confederacy of tribes in western Iran. It was the Persians, however, who proved to be the main beneficiaries. The Persian state emerged in the 7th century BC on the edge of the area dominated by Assyria and in 550 BC its ruler, Cyrus (559-530 BC), defeated an invading Median army at Pasargadae. The next 11 years saw attempts to stop the growth of Persian power by both Croesus of Lydia and Nabonidus of Babylon. Both were defeated, leaving Cyrus in possession of Anatolia, the Levant and Mesopotamia.

The absorption of Lydian territory into Cyrus's empire brought Persia into contact with the Greeks. He then turned his attention eastwards, gaining control of much of Afghanistan and south central Asia. Though Cyrus's successor, Cambyses (530-522 BC), added Egypt to the emppire in 525 BC, his death was followed by the first of several upheavals within the empire as uncertainty over the succession encouraged widespread revolts.

These were quickly suppressed by Darius (522-486 BC), who also incorporated northwest India into the empire. The northwestern boundary of the empire remained a problem, but after the failure of expeditions into Europeby Darius and Xerxes (486-465 BC), the Persian protected their interests by a series of peace treaties with the Greek states.

Achaemenid rule was brought to an end by the invasion of Alexander the Great in 334 BC. Dynastic struggles in the 330s may have had an effect, but no entirely satisfactory explanation has been given for the rapidity with which the Achaemenid empire fell.

The Parthian empire
After Alexander's death, Iran and its neighbouring territories became part of the Seleucid kingdom. In the 3rd century BC internal disputes and conflict with other Hellenistic kingdoms weakened Seleucid control of their eastern territories. Bactria broke away to become an independent kingdom, and the province of Parthia and Hyrcania were taken over by Arsaces, leader of the Parni in 238.

The early history of the new kingdom of Parthia is uncertain, but under Mithradates I (171-138 BC) its territory was extended into Mesopotamia and as far east as the mouth of the Indus, its success, like that of Sasanid Persia later, was largely the result of the use of mounted archers and armoured cavalry. In the years after Mithradate's death the empire was threatened by the Tocharians and the Shakas in the east, but order was restored by Mithradates II (123-87 BC). From the first century BC onwards, in spite of further Shaka incursions from the east, the main threat to Parthian security was Rome. But although there were a large number of wars between the two empires, they were well matched militarily and Arsacid, or Parthian rule, remained secure until it was challenged from within.

Sasanid Persia
Considerable autonomy was left in the hands of the local ruling families, and it was from one of these in Persia that the new rulers of Persia arose. The first Sasanid ruler, Ardashir, defeated his Saracid overlord Ardavan in 224 AD and rapidly took control of the whole of Parthia's empire and the areas beyond. Roman and Byzantine rule in Mesopotamia, Syria and eastern Anatolia was constantly challenged over the next centuries. The last century of Parthian rule had seen the rise of the Kushana empire in the east. This ended in 225 and Gandhara, Bactria and Sogdiana were brought under Sasanid control. From the 4th century this territory was threatened by Hephthalite and Chionite Huns and in the 6th century by the Turks.

The Arabs were a constant presence to the southwest off Persia's empires. The Achaemenids had established some control over northern Arabia, but in the Parthian period an independent state of Characene emerged at the head of the Persian Gulf, whose rulers styled themselves "kings of the Arabs". The Sasanids ended the independence of characene but maintained friendly relations with the Lakhmid Arab kingdom of Hira in western Mesopotamia which supported them against the Romans. Southern Arabia was never brought under Persian control, and in c. 604, after the Sasanid Chosroes II had ended Lakhmid independence, the Persians were defeated in battle by a confederacy of Arabs from the south. Success created confidence and increased Arab unity to such an extent that with further victories at Al Qadisiyya (637) and Nihavand (642) they brought Sasanid power an end.