Around this time, Cyrus II (Cyrus the Great) defeated Astyages of Media and took control of key Median centers such as Ecbatana. This is widely treated as the starting point of the Achaemenid Empire’s rapid expansion from a Persian kingdom into a multi-regional empire.
Cyrus defeated the Lydian king Croesus and captured Sardis, bringing wealthy western Anatolia under Persian control. This conquest expanded Achaemenid power toward the Aegean and set the stage for later conflicts involving Greek cities in the region.
Cyrus entered Babylon in 539 BCE, adding Mesopotamia—one of the ancient world’s most important economic and cultural regions—to Achaemenid rule. Control of Babylon strengthened the empire’s resources and legitimacy by linking Persian kingship to long-standing traditions of Mesopotamian rule.
After Babylon fell, an official inscription now known as the Cyrus Cylinder was deposited in the city as a foundation text. Written in Akkadian cuneiform, it presents Cyrus’s rule in terms familiar to Babylonian royal ideology, including restoring temples and ordering the city’s affairs.
In 525 BCE, Cambyses II defeated Egypt, bringing another major, long-established kingdom under Achaemenid control. This conquest extended the empire into North Africa and made Persia the dominant power across a vast zone from the Nile to Central and Western Asia.
After the death of Cambyses II, Darius I gained power amid revolts and competing claims to kingship. His reign is a turning point: he reasserted central authority and reshaped the empire’s administration, helping it function as a durable, multi-ethnic state.
Darius ordered the Behistun (Bisotun) relief and inscription to record his rise to power and his suppression of rebellions. The monument’s trilingual text (Old Persian, Elamite, and Babylonian) was a major statement of legitimacy and later became crucial for deciphering cuneiform.
Darius founded Persepolis as a royal capital and ceremonial center, beginning major construction around 518 BCE. Its palaces and reliefs projected imperial power by showing delegations from many regions bringing tribute, reflecting the empire’s broad reach.
Greek cities in Ionia rebelled against Achaemenid control, and the revolt drew support from Athens and Eretria. Although Persia ultimately suppressed the revolt, it heightened tensions and helped trigger later Persian expeditions against mainland Greece.
In September 490 BCE, Athenians and Plataeans defeated a Persian expedition at Marathon. The battle did not end Persian power, but it blocked the immediate attempt to punish Athens and became a major moment in the wider Greco-Persian conflict.
In 480 BCE, Xerxes I launched a major invasion of Greece. Persian forces won the land battle at Thermopylae, but later that year the Greek fleet defeated Persia at Salamis, disrupting Persian plans and forcing a major strategic adjustment.
In 479 BCE, allied Greek forces defeated the Persian army at Plataea. After this defeat, Persia did not attempt another full-scale invasion of Greece, and the conflict shifted toward naval and coastal struggles in the Aegean region.
A later agreement often called the Peace of Callias is commonly placed around 450/449 BCE, though ancient evidence is debated. In broad terms, it is associated with reduced direct fighting between Athens and Persia and a more stable balance of power in the Aegean.
In 333 BCE, Alexander the Great defeated Darius III at Issus, capturing Darius’s family and pushing Persian forces out of much of the eastern Mediterranean coast. The battle showed that the empire’s western defenses could be broken by a highly mobile, coordinated Macedonian army.
On October 1, 331 BCE, Alexander defeated Darius III again at Gaugamela, a decisive battle that opened the way to the imperial centers. Afterward, Alexander took key cities and treasuries, leaving the Achaemenid state unable to recover its former authority.
In 330 BCE, Alexander entered Persepolis, seized its treasury, and burned major parts of the palace complex, including the palace of Xerxes. The destruction became a powerful symbol of the end of Achaemenid royal display at its most famous ceremonial capital.
In 330 BCE, Darius III was deposed and killed while fleeing east, ending the Achaemenid dynasty’s reign. With the king dead and the imperial centers in Macedonian hands, the empire’s political structure collapsed and was replaced by Alexander’s new regime and, later, Hellenistic successor states.
Achaemenid Empire (c. 550–330 BCE)