Rulers of the Persian Empire: Expansionism of Cyrus and Darius

Persian Empire Tombs of Naqsh-e Rustam, Marvdascht, Fars, Iran, Asia
The Achaemenid Tombs of Naqsh-e Rustam including that of Darius II, Marvdascht, Fars, Iran, Asia. Gilles Barbier / Getty Images

At its height, in about 500 BCE, the founding dynasty of the Persian Empire called the Achaemenids conquered Asia as far as the Indus River, Greece, and North Africa including what is now Egypt and Libya. It also included modern-day Iraq (ancient Mesopotamia), Afghanistan, as well as probably modern-day Yemen and Asia Minor.

The impact of the expansionism of the Persians was felt in 1935 when Reza Shah Pahlavi changed the name of the country known as Persia to Iran. "Eran" was what the ancient Persian kings called the people they ruled that we now know as the Persian Empire. The original Persians were Aryan speakers, a linguistic group that encompassed a large number of sedentary and nomadic people of Central Asia.


The beginning of the Persian empire has been set at different times by different scholars, but the real force behind the expansion was Cyrus II, also known as Cyrus the Great (ca. 600–530 BCE). The Persian Empire was the largest in history for the next two centuries until it was conquered by Macedonian adventurer, Alexander the Great, who established an even greater empire, in which Persia was only a part.

Historians typically divide the empire into five periods.

  • Achaemenid Empire (550–330 BCE)
  • Seleucid Empire (330–170 BCE), established by Alexander the Great and also called the Hellenistic Period
  • Parthian Dynasty (170 BCE–226 CE)
  • Sassanid (or Sasanian) Dynasty (226–651 CE)

Dynastic Rulers

Tomb of Cyrus the Great at Pasargadae
Achaemenian tomb of Cyrus II, 559-530 BC, on Murghab Plain, restored by Alexander the Great in 324 BC, Pasargadae, Iran.  Christopher Rennie / robertharding / Getty Images Plus

Cyrus the Great (ruled 559–530) was the founder of the Achaemenid dynasty. His first capital was at Hamadan (Ecbatana) but eventually moved it to Pasargadae. The Achaemenids created the royal road from Susa to Sardis that later helped the Parthians establish the Silk Road and a postal system. Cyrus's son Cambyses II (559–522, r. 530–522 BCE) and then Darius I (also known as Darius the Great, 550–487 BCE, r. 522–487 CCE) further expanded the empire; but when Darius invaded Greece, he started the disastrous Persian War (492–449/448 BCE); after Darius died, his successor Xerxes (519–465, r. 522–465) invaded Greece again.

Darius and Xerxes lost the Greco-Persian wars, in effect establishing an empire for Athens, but later Persian rulers continued to interfere in Greek affairs. Artaxerxes II (r. 465–424 BCE), who reigned for 45 years, built monuments and shrines. Then, in 330 BCE, Macedonian Greeks led by Alexander the Great overthrew the final Achaemenid king, Darius III (381–330 BCE).

Seleucid, Parthian, Sassanid Dynasties

After Alexander died, his empire was broken up into pieces ruled by Alexanders' generals known as the Diadochi. Persia was given to his general Seleucus, who established what was called the Seleucid Empire. The Seleucids were all Greek kings who ruled parts of the empire between 312–64 BCE.

The Persians regained control under the Parthians, although they were continued to be heavily influenced by the Greeks. The Parthian Dynasty (170 BCE–224 CE) was ruled by the Arsacids, named for the founder Arsaces I, leader of the Parni (an east Iranian tribe) who took control of the former Persian satrapy of Parthia.

In 224 CE, Ardashir I, the first king of the final pre-Islamic Persian dynasty, the city-building Sassanids or Sassanians defeated the last king of the Arsacid dynasty, Artabanus V, in battle. Ardashir came from the (southwestern) Fars province, near Persepolis.

Naqsh-e Rustam

Although the founder of the Persian empire Cyrus the Great was buried in a built tomb at his capital of Pasargadae, the body of his successor Darius the Great was placed in a rock-cut tomb at the site of Naqsh-e Rustam (Naqs-e Rostam). Naqsh-e Rustam is a cliff face, in Fars, about 4 miles northwest of Persepolis.

The cliff is the site of four royal tombs of the Achaemenids: the other three burials are copies of Darius's tomb and thought to have been used for other Achaemenid kings—the contents were looted in antiquity. The cliff has inscriptions and reliefs from pre-Achaemenid, Achaemenid, and Sasanian Periods. A tower (Kabah-i Zardusht, "the cube of Zoroaster") standing in front of Darius's tomb was built as early the first half of the 6th century BCE. Its original purpose is debated, but Inscribed on the tower are the deeds of the Sassanian king Shapur.

Religion and the Persians

There is some evidence that the earliest Achaemenid kings may have been Zoroastrian, but not all scholars are agreed. Cyrus the Great was known for his religious tolerance with regard to the Jews of the Babylonian Exile, according to inscriptions on the Cyrus Cylinder and existing documents in the Old Testament of the Bible. Most of the Sassanians espoused the Zoroastrian religion, with varying levels of tolerance for non-believers, including the early Christian church.

End of the Empire

By the sixth century CE, conflicts grew stronger between the Sasanian dynasty of the Persian Empire and the increasingly powerful Christian Roman Empire, involving religion, but primarily trade and land wars. Squabbles between Syria and other contested provinces led to frequent, debilitating border disputes. Such efforts drained the Sassanians as well as the Romans who were also ending their empire.

The spread of Sasanian military to cover the four sections (spahbeds) of the Persian empire (Khurasan, Khurbarãn, Nimroz, and Azerbaijan), each with its own general, meant that troops were too thinly spread to resist the Arabs. The Sassanids were defeated by Arab caliphs in the mid-7th century CE, and by 651, the Persian empire was ended.


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Gill, N.S. "Rulers of the Persian Empire: Expansionism of Cyrus and Darius." ThoughtCo, Apr. 5, 2023, Gill, N.S. (2023, April 5). Rulers of the Persian Empire: Expansionism of Cyrus and Darius. Retrieved from Gill, N.S. "Rulers of the Persian Empire: Expansionism of Cyrus and Darius." ThoughtCo. (accessed June 8, 2023).