Cyrus II’s forces defeated the Neo-Babylonian army near Opis on the Tigris, breaking organized resistance and opening the route to Babylon.
After Opis, the Persians captured Sippar without fighting; Nabonidus fled, accelerating the collapse of Neo-Babylonian control in the region.
Persian forces under Ugbaru/Gubaru entered Babylon without a battle and detained Nabonidus, marking the effective takeover of the city.
Cyrus formally entered Babylon later in October 539 BCE and assumed kingship; Persian policy emphasized order and protection of major cult sites and rites.
A royal Akkadian inscription (the “Cyrus Cylinder”) was produced after the conquest, presenting Cyrus as chosen by Marduk, restoring cults, and reversing some forced labor and displacements as part of legitimizing Persian rule in Babylonia.
At the Babylonian New Year (Akitu) festival, Cambyses (Cyrus’ son) took part in temple rituals in Babylon, reflecting early Achaemenid efforts to align rule with Babylonian religious-political traditions.
Babylonian records place Cambyses as governor over northern Babylonia (including Babylon) for part of 538 BCE, illustrating how the new regime used royal family members and established administrative practice to manage Mesopotamia.
Cyrus’ government created a combined satrapy often described as “Babylonia and Eber-Nāri,” linking Mesopotamia with the western territories beyond the Euphrates under a single satrapal administration based in Babylon.
After Cyrus’ death, Cambyses II became sole king, continuing Achaemenid imperial structures that governed Babylonia within the wider empire.
During the succession crisis after Cambyses’ death, a Babylonian rebel (Nidintu-Bêl), styling himself Nebuchadnezzar, took control in Babylonia—showing persistent local capacity to mobilize royal ideology against Persian rule.
Darius I campaigned against Nidintu-Bêl and defeated his forces in battles recorded in the Behistun account, restoring Achaemenid control over Babylonia by late 522 BCE.
A second Babylonian claimant (Arakha), also adopting the name “Nebuchadnezzar,” briefly ruled before Darius’ forces suppressed the rebellion (part of the wider revolts summarized in the Behistun narrative).
Babylonia experienced major revolts early in Xerxes I’s reign (484–482 BCE). Ancient and modern accounts describe severe reprisals and major disruptions to Babylon’s religious-political institutions, though details and extent are debated.
Conquest of Babylon and Persian administration in Mesopotamia (539–480 BCE)
