It pleased Darius— That is, Cyaxares, whose father is called Assuerus, in the book of Tobit, Tob 14:15 as he is also by Daniel, chap. Daniel 9:1 meaning in both places Astyages, or the king of Media, who concurred with the Assyrian monarch in the destruction of Nineveh. Herodotus and Xenophon make mention of an ancient gold coin called Δαριεκος or Daric, as is presumed by many writers, from this king; from the first Darius, according to Suidas, or one prior to Hystaspes. This coin seems to have been called by the like name after the captivity in Ezra 2:69 and 1 Chronicles 29:7 in the original. Sir Isaac Newton says he had seen one of them, and that it was stamped on one side with the effigies of an archer crowned with a spiked crown, with a bow in his left, and an arrow in his right hand, and clothed with a long robe, that it weighed two attic drams, and was of the value of the attic stater. Chron. of Ant. Kingd. p. 319.
The war with the Chaldeans, which ended in the destruction of Babylon, seems to have commenced originally on the part of the Medes, over whom the Babylonian queen Nitocris, according to Herodotus, had kept a jealous and watchful eye. Jeremiah, Jeremiah 51:11; Jeremiah 51:28., mentions the kings of the Medes only as raised up against Babylon, and so Isaiah 13:17, but elsewhere he joins the Elamites with them; and Thucydides generally calls the Persians Medes only. However, when Babylon was taken and subdued by the united powers of Media and Persia, Cyrus was probably induced to set over it this king of the Medes, in order to make the union of the two nations more easy, and to prepare matters better for the full establishment of the Persian empire. Cyaxares, as is generally agreed, reigned not more than two years; and during that term being only a sort of viceroy, or at least dependent upon Cyrus, the whole period of nine years is ascribed by Ptolemy to Cyrus, and no notice taken of Darius at all.
An hundred and twenty princes— According to the number of provinces which were subject to the Medo-Persian empire. These were afterwards enlarged to an hundred and twenty-seven, by the victories of Cambyses and Darius Hystaspis. See Esther 1:1. Darius divides the kingdom, and orders that an account of the whole should be rendered to the three principal officers, to whom he gives the superintendance over the rest. Darius preserved to Daniel the rank and employment which Belshazzar gave him a little before his death. Several writers have thought, that after Darius had conquered Babylon he returned to Media, and took Daniel with him; and that it was there that the establishments here spoken of were made. But, if this was not done at Babylon, it is much more likely to have been done at Shushan than in Media. See chap. Daniel 8:2 and Calmet.