A short empire and a sudden end
The word “decline” suggests a slow fade, but the evidence points the other way. The Neo-Babylonian empire lasted from 626 BCE, when Nabopolassar took the throne, until 539 BCE, a span of under ninety years. Its great builder Nebuchadnezzar II died in 562 BCE, and within a generation the empire had been taken in a single campaign. The question behind the fall of Babylon is why a rich state fell so fast. The honest answer is that scholars see several causes together and disagree about how much weight each deserves, partly because the most vivid accounts come from the winners.
After Nebuchadnezzar
Nebuchadnezzar’s death was followed by short reigns: his son Amel-Marduk (562 to 560 BCE), his son-in-law Neriglissar (560 to 556), and Neriglissar’s young son Labashi-Marduk, who was removed within months. Nabonidus then took the throne in 556 BCE. He did not belong to the royal family, and his mother, Adda-guppi, appears to have been closely associated with the temple of the moon god Sin at Harran. Court intrigues like these weakened the dynasty’s claim to continuity, though the empire itself stayed in working order.
Nabonidus and Tayma
Nabonidus is a controversial figure. He rebuilt temples across Babylonia and showed real interest in the past, searching for ancient foundation records, and some have called him an antiquarian king. But his devotion to Sin, whom he elevated, seems to have unsettled some Babylonians who held Marduk to be the chief god.
Around 553 BCE he left Babylon for the oasis of Tayma in northern Arabia and remained there for roughly ten years, while his son Belshazzar acted as regent in Babylonia. Why he went is unclear. Proposed reasons include control of caravan routes, the wealth of Arabian trade, a personal religious preference, or a campaign that turned into a stay. An inscription found in the region records his presence.
A consequence of the long absence is better documented: the New Year festival, the Akitu, is reported in the Nabonidus Chronicle as not being held in those years, since it required the king to take part. The festival was central to Babylonian religion, because it reaffirmed both Marduk’s role and the king’s right to rule.
The priesthood and the question of bias
Sources hostile to Nabonidus claim that the Marduk priesthood turned against him. One is the so-called Verse Account, a poem that mocks his religious reforms. Another is the Cyrus Cylinder, a Persian text that describes Nabonidus as an impious ruler and presents Cyrus as Marduk’s chosen king. Both were written by people with a reason to justify the conquest.
Modern historians treat them cautiously. Nabonidus’s own inscriptions show a king who presented himself as a pious restorer of temples. It seems likely that his religious choices irritated some in Babylon’s elite, but how widely and how seriously is hard to judge. Other pressures may have mattered too, such as the cost of maintaining an empire, uneven harvests and strain between city and crown. The evidence is incomplete.
The Persian conquest
Cyrus, the king of Persia, had been expanding quickly. He defeated the Median king Astyages around 550 BCE, took Lydia (the Lydian kingdom of Croesus, whose capital was Sardis) around 546, and then turned to the east and finally to Babylonia. The sequence in the Nabonidus Chronicle, a contemporary Babylonian text, is the best guide:
- In autumn 539 BCE, Cyrus’s army met Babylonian forces at Opis, on the Tigris, and defeated them.
- Sippar surrendered soon after, and Nabonidus fled.
- On 16 Tashritu, in October 539 BCE, troops under a general named Gubaru (often identified with the figure Ugbaru) entered Babylon without a battle, according to the Chronicle.
- Cyrus himself entered a little over two weeks later and was welcomed, according to Persian and Babylonian sources, which also favour him.
Nabonidus was captured. The city was not sacked on this account, and the temples continued to operate. Later Greek stories, such as Herodotus’s claim that Cyrus diverted the Euphrates to enter along the riverbed, are unconfirmed and do not match the Chronicle. The biblical account of Belshazzar’s feast, in which the king is killed on the night of the city’s fall, is likewise a later literary tradition. Belshazzar was real, but he was crown prince and regent, not king, and the Chronicle does not describe such a night.
The Cyrus Cylinder is often described as an early charter of human rights, but historians view that reading with caution. It is better understood as a royal inscription in a Mesopotamian tradition, announcing that Cyrus restored the gods’ images and let displaced peoples return home. The takeover followed the pattern of the Achaemenid conquests and fall in later reigns.
Babylon under the Persians and afterwards
Babylon did not disappear. It became the administrative centre of a Persian province within the satrapy system and remained rich and important. Two revolts under men who took the name Nebuchadnezzar broke out in 522 to 521 BCE against Darius I, and another occurred in the reign of Xerxes, around 484 BCE, after which Babylon lost some of its privileges.
When Alexander arrived in 331 BCE, after Gaugamela, where it came down to Alexander versus Darius for the Persian throne, the city opened to him, and he died there in 323. His successor Seleucus founded a new capital, Seleucia on the Tigris, around 305 BCE, drawing people and commerce away. Even so, Babylon’s temples and scholars kept working for centuries, which is why the latest cuneiform tablets date to the first century CE.