The Medes are credited with the unification of Iran as a nation and empire (625–559 BC), the largest of its day, until Cyrus the Great established a unified empire of the Medes and Persians leading to the Achaemenid Empire (559–330 BC), and further unification between peoples and cultures. After Cyrus' death, his son Cambyses continued his father's work of conquest, making significant gains in Egypt. Following a power struggle after Cambyses' death, Darius I was declared king (ruled 522–486 BC). Under Cyrus the Great and Darius the Great, the Persian Empire eventually became the largest and most powerful empire in human history up until that point.The borders of the Persian empire stretched from the Indus and Oxus Rivers in the east to the Mediterranean Sea in the west, extending through Anatolia (modern day Turkey) and Egypt..
The Achaemenid Empire at its greatest extent, at about 500 BC
In
499 BC Athens lent support to a revolt in Miletus which resulted in the
sacking of Sardis. This led to an Achaemenid campaign against Greece
known as the Greco-Persian Wars which lasted the first half of the 5th
century BC. During the Greco-Persian wars Persia made some major
advantages and razed Athens in 480 BC, But after a string of Greek
victories the Persians were forced to withdraw. Fighting ended with the
peace of Callias in 449 BC.
The rules and ethics emanating
from Zoroaster's teachings were strictly followed by the Achaemenids
who introduced and adopted policies based on human rights, equality and
banning of slavery. Zoroastrianism spread unimposed during the time of
the Achaemenids and through contacts with the exiled Jewish people in
Babylon freed by Cyrus, Zoroastrian concepts further propagated and
influenced the Abrahamic religions. The Golden Age of Athens marked by
Aristotle, Plato and Socrates also came about during the Achaemenid
period while their contacts with Persia and the Near East abounded. The
peace, tranquility, security and prosperity that were afforded to the
people of the Near East and Southeastern Europe proved to be a rare
historical occurrence, an unparalleled period where commerce prospered,
and the standard of living for all people of the region improved.
In
334 BC, Alexander the Macedonian invaded the Achaemenid Empire,
defeating the last Achaemenid Emperor Darius III at the Battle of Issus
in 333 BC. He left the annexed territory in 328–327. In each of the
former Achaemenid territories he installed his own officers as
caretakers, which led to friction and ultimately to the partitioning of
the former empire after Alexander's death.
The
Parthian Empire (238 BC–226 AD), led by the Arsacid Dynasty, was the
third Iranian kingdom to dominate the Iranian plateau, after defeating
the Greek Seleucid Empire, beginning in the late 3rd century BC, and
intermittently controlled Mesopotamia between ca. 150 BC and 224 AD.
These were the third native dynasty of ancient Iran and lasted five
centuries. After the conquests of Media, Assyria, Babylonia and Elam,
the Parthians had to organize their empire. The former elites of these
countries were Greek, and the new rulers had to adapt to their customs
if they wanted their rule to last. As a result, the cities retained
their ancient rights and civil administrations remained more or less
undisturbed.
Parthia was the arch-enemy of the Roman
Empire in the east, limiting Rome's expansion beyond Cappadocia
(central Anatolia). By using a heavily armed and armoured cataphract
cavalry, and lightly armed but highly mobile mounted archers, the
Parthians "held their own against Rome for almost 300 years".Rome's
acclaimed general Mark Antony led a disastrous campaign against the
Parthians in 36 BC, in which he lost 32,000 men. By the time of Roman
emperor Augustus, Rome and Parthia were settling some of their
differences through diplomacy. By this time, Parthia had acquired an
assortment of golden eagles, the cherished standards of Rome's legions,
captured from Mark Antony, and Crassus, who suffered a defeat at
Carrhae in 53 BC.
The end of the Parthian Empire came in 224 AD,
when the empire was loosely organized and the last king was defeated by
Ardashir I, one of the empire's vassals. Ardashir I then went on to
create the Sassanid Empire. Soon he started reforming the country both
economically and militarily. The Sassanids established an empire
roughly within the frontiers achieved by the Achaemenids, referring to
it as Erânshahr or Iranshahr, , "Dominion of the Aryans", (i.e. of
Iranians), with their capital at Ctesiphon.Unlike the diadochic
Seleucids and the succeeding Arsacids, who used a vassalary system, the
Sassanids—like the Achaemenids—had a system of governors (MP: shahrab)
personally appointed by the Emperor and directed by the central
government.
The Romans suffered repeated losses particularly by
Ardashir I, Shapur I, and Shapur II.[49] During their reign, Sassanid
battles with the Roman Empire caused such pessimism in Rome that the
historian Cassius Dio wrote:
“ Here was a source of great fear to
us. So formidable does the Sassanid king seem to our eastern legions,
that some are liable to go over to him, and others are unwilling to
fight at all.”
In 632 raiders from the Arab peninsula
began attacking the Sassanid Empire. Iran was defeated in the Battle of
al-Qâdisiyah, paving way for the Islamic conquest of Persia.
During
Parthian, and later Sassanid era, trade on the Silk Road was a
significant factor in the development of the great civilizations of
China, Egypt, Mesopotamia, Persia, Indian subcontinent, and Rome, and
helped to lay the foundations for the modern world. Parthian remains
display classical Greek influences in some instances and retain their
oriental mode in others, a clear expression of the cultural diversity
that characterized Parthian art and life.The Parthians were innovators
of many architecture designs such as that of Ctesiphon, which later
influenced European Romanesque architecture.Under the Sassanids, Iran
expanded relations with China. Arts, music, and architecture greatly
flourished, and centers such as the School of Nisibis and Academy of
Gundishapur became world renowned centers of science and scholarship.



