Daniel was a young man of the upper crust of Jewish society who was taken captive by Nebuchadnezzar II, king of Babylon and the Chaldean dynasty. Nebudchadnezzar endeavored to remove all traces of Daniel's nationality and religion. For this reason they strove to change Daniel's name to Belteshazzar:
7 And the chief of the eunuchs gave them names: Daniel he called Belteshazzar, Hananiah he called Shadrach, Mishael he called Meshach, and Azariah he called Abednego. (Dan. 1:7 ESV)
(see also: 2:26; 4:8-9, 18-19; 5:12; 10:1).