One principal source of information about the rise of Cyrus the Great (559–530 B.C.) is the so-called Nabonidus Chronicle. The chronicle consists of a series of cuneiform tablets (such as the 5.5-inch-high fragment shown) listing important events that took place during the reign of the Babylonian king Nabonidus (555–539 B.C.).

Following the death of the Babylonian king Nebuchadnezzar (604–562 B.C.), Babylonia was briefly ruled by the king’s son, son-in-law and grandson. In 555 B.C. the latter was murdered in a conspiracy that placed Nabonidus, a distinguished general, on the throne. Like his priestess mother, Nabonidus was a deeply religious man and a devotee of the moon-god Sin. The 2-foot-tall basalt stela shownis thought to depict Nabonidus, who wears a spiked helmet and raises his right hand towards symbols of Sin (circle with crescent), the sun-god Shamash (winged disk) and the love-war goddess Ishtar (a seven-pointed star representing the planet Venus).

According to the chronicle, Nabonidus had a dream early in his reign in which Marduk, Babylon’s supreme deity, instructed him to rebuild the deserted Sin temple in the city of Harran, which had fallen to a people called the Medes. When Cyrus the Great conquered the Medes, Nabonidus believed the Persian king was acting as Marduk’s agent.

Nabonidus’s rebuilding of the Sin temple in Harran and his other religious innovations alienated many of Babylonia’s more conservative priests. Around 554 B.C., perhaps out of disappointment over his subjects’ impiety, Nabonidus named his son, Belshazzar, as regent and left Babylon to spend ten years in voluntary exile in northwest Arabia. The king’s absence meant that the annual Babylonian New Year Festival (celebrated to ensure the prosperity of the realm) could not take place—creating further resentment against the already weakened king.

In 539 B.C., about five years after Nabonidus returned to Babylon, Cyrus the Great took control of the city without opposition. Greek accounts indicate that Nabonidus was either sent to govern a province in southern Persia or murdered. According to the biblical book of Daniel, his son Belshazzar was put to death.