Stephanie Dalley, in Myths from Mesopotamia, writes that "the Epic of Anzu is principally known in two versions: an Old Babylonian version of the early second millennium [BC], giving the hero as Ningursu; and 'The Standard Babylonian' version, dating to the first millennium BC, which appears to be the most quoted version, with the hero as Ninurta". However, the Anzu character does not appear as often in some other writings, as noted below.