Nabû-nāṣir, inscribed in cuneiform as AG-PAB or AG-ŠEŠ-ir, Greek: Ναβονάσσαρος, whence "Nabonassar", and meaning "Nabû (is) protector", was the king of Babylon 747–734 BCE. He deposed a foreign Chaldean usurper named Nabu-shuma-ishkun, bringing native rule back to Babylon after 23 years of Chaldean rule. His reign saw the beginning of a new era characterized by the systematic maintenance of chronologically precise historical records. Both the Babylonian Chronicle and the Ptolemaic Canon begin with his accession to the throne. He was contemporary with the Assyrian kings Aššur-nirarī V (755–745 BCE) and Tiglath-Pileser III, the latter under whom he became a vassal, and the Elamite kings Humban-Tahrah I (–743 BCE) and Humban-Nikaš I (742–717 BCE).