Belshazzar was the son and crown prince of Nabonidus, the last king of the Neo-Babylonian Empire. Through his mother, he might have been a grandson of Nebuchadnezzar II, though this is not certain and the claims to kinship with Nebuchadnezzar may have originated from royal propaganda.
The Nabonidus Chronicle, an ancient Babylonian text which chronicles the reign of Belshazzar's father and also documents the period during which Belshazzar was regent in Babylon
Stele depicting Nabonidus, Belshazzar's father
This clay cylinder records the restoration of Sin's ziggurat at Ur by Nabonidus, and also asks him to protect Nabonidus and his son, Belshazzar. From Ur, Iraq
This administrative document is dated to the "24th day of Kislimu in the 11th year of Nabonidus, king of Babylon". It mentions a slave of Bel-sharra-usur (Belshazzar), son of the king. Although Belshazzar is acting as a regent, the formal date shows that Nabonidus is still the reigning king. From Borsippa, Iraq
Nabonidus was the last king of the Neo-Babylonian Empire, ruling from 556 BC to the fall of Babylon to the Achaemenian Empire under Cyrus the Great in 539 BC. Nabonidus was the last native ruler of ancient Mesopotamia, the end of his reign marking the end of thousands of years of Sumero-Akkadian states, kingdoms and empires. He was also the last independent king of Babylon. Regarded as one of the most vibrant and individualistic rulers of his time, Nabonidus is characterised by some scholars as an unorthodox religious reformer and as the first archaeologist.
Nabonidus, detail of a stele in the British Museum, probably from Babylon, Iraq
Relief of Ashurbanipal, who ruled as king of Assyria 669–631 BC. Nabonidus emulated elements of Ashurbanipal and his dynasty, the Sargonids. Some historians believe that Nabonidus was a descendant of Ashurbanipal, or Ashurbanipal's father Esarhaddon.
Nabonidus as depicted in a stele from Harran
A granite stele of Nabonidus