In 1924 publication was made of the decipherment of an ancient cuneiform text described as the “Verse Account of Nabonidus,” and through it valuable information was brought to light clearly corroborating Belshazzar’s kingly position at Babylon and explaining the manner of his becoming coregent with Nabonidus. Concerning Nabonidus’ conquest of Tema in his third year of rule, a portion of the text says: “He entrusted the ‘Camp’ to his oldest (son), the firstborn [Belshazzar], the troops everywhere in the country he ordered under his (command). He let (everything) go, entrusted the kingship to him and, himself, he [Nabonidus] started out for a long journey, the (military) forces of Akkad marching with him; he turned towards Tema (deep) in the west.” (Ancient Near Eastern Texts, edited by J. Pritchard, 1974, p. 313) Thus, Belshazzar definitely exercised royal authority from Nabonidus’ third year on, and this event likely corresponds with Daniel’s reference to “the first year of Belshazzar the king of Babylon.”​—Da 7:1.

In another document, the Nabonidus Chronicle, a statement is found with regard to Nabonidus’ seventh, ninth, tenth, and eleventh regnal years. It reads: “The king (was) in Tema (while) the prince, the officers, and his army (were) in Akkad [Babylonia].” (Assyrian and Babylonian Chronicles, by A. K. Grayson, 1975, p. 108) Apparently Nabonidus spent much of his reign away from Babylon, and while not relinquishing his position as supreme ruler, he entrusted administrative authority to his son Belshazzar to act during his absence. This is evident from a number of texts recovered from the ancient archives proving that Belshazzar exercised royal prerogatives, that he issued orders and commands. Matters handled by Belshazzar in certain documents and orders were those that would normally have been handled by Nabonidus, as supreme ruler, had he been present.