Ephrem the Syrian : Darius, as he loved quietness and inactivity and found work and business unpleasing, left the care of the empire to his prefects, and for this reason the Scripture adds, he set over the kingdom satraps, that is, 120 governors. And over them he placed three presidents, including Daniel. Then they asked him to set an interdict according to the law of the Medes and Persians. Indeed, among the Persians and the Medes, a law stated that when the king had set a certain rule, it was not permitted to rescind it. So the satraps asked the king for this kind of firm and immutable decree; and they were certain that the king would have not rescinded such a decree in order to save Daniel. It is likely that Daniel was not present in the hall of justice on that day, when the king argued from morning till evening with his satraps in order to save Daniel. If he had been present, he would have immediately confessed that he had prayed [to God], and after the confession of the crime the trial would have not been extended until evening. — COMMENTARY ON Daniel 6:1-15 Jerome : Verse 8. "Now therefore, O king, confirm the measure and write the decree so that it may not be altered, according to the custom established by the Medes and Persians." It is perfectly evident, as we have remarked above, that there was only one kingdom of the Medes and Persians both, under the rule of Darius and Cyrus. — St. Jerome, Commentary on Daniel, CHAPTER SIX