This last chapter of the Book of Daniel is often referred to as the story of Bel, the god, and the dragon. Daniel will show how each one was useless. Once again, this chapter is only in the Greek Septuagint, so that it is often called apocryphal. This story takes place at the later part of the life of Daniel, since Cyrus the Persian (598-530 BCE) was the King. His rule in Persia began in 559 BCE and lasted about 30 years. Here, he is still only the king of Persia that he received from his father, King Astyages (585-550 BCE). The sister of King Astyages was the wife of King Nebuchadnezzar of Babylon. Thus, you can see the connection, as Cyprus would have been the nephew of the Babylonian king. Eventually, Cyrus took over Babylon in 539 BCE.
Finally, Daniel came in to see the king. As with his companions, King Nebuchadnezzar had given Daniel a Babylonian name, Belteshazzar, based on the name of his Babylonian god, Bel. The king realized that Daniel, like Joseph with the Egyptian Pharaoh, had special spiritual powers. After all, in chapter 2, Daniel knew and interpreted his dream. The king called Daniel the chief of the magicians. He thought that no mystery would be too difficult for Daniel, because of the special divine powers that he had. Thus, the king was not afraid to tell Daniel, or Belteshazzar, his dream or ask for an interpretation.
Yahweh says that he was going to punish Bel, the god of Mesopotamia. Thus with the defeat of Babylon, the god Bel was also defeated. The punishment was that Bel had to throw up what he had eaten. All those nations where Bel was their god would no longer stream to his temple, because Babylon had fallen.
This oracle of Yahweh says that Jeremiah should proclaim to the various nations and not conceal the fact that Babylon was taken. However, Jeremiah died in 582 BCE and Babylon was defeated in 539 BCE, over forty years after the death of Jeremiah. Previously, Jeremiah had been very favorable to King Nebuchadnezzar of Babylon. Here he was told to set up a banner that said that Babylon with its false idol gods was put to shame and dismayed, especially two Babylonian gods, Bel and Merodach. Bel was another encompassing word for master or lord as some of the Hebrew words used about Yahweh. It also had some connection to Baal in the Mesopotamian area. Merodach or Marduk was the principal god or patron of the city of Babylon. Thus these two major Babylonian gods would be put to shame and dismayed. Much the same can be found in Isaiah, chapter 46.
Second Isaiah talks about the failure of the Babylonian gods. Bel or Bel-Marduk was the chief god of the Babylonians. He was like the lord god. Nebo or Nabu was the son of Marduk, a Babylonian god that was a scribe or wise person. Both of them failed. They had to bow down and stoop before others. These gods had to be carried away on the backs of beasts and animals, since they were incapable of helping themselves as they went into captivity.