Taken from: http://biblehub.com/nasb/daniel/5-2.htm
That the king and his princes, his wives, and his concubines, might drink therein – Nothing is too sacred to be profaned when men are under the influence of wine. They do not hesitate to desecrate the holiest things, and vessels taken from the altar of God are regarded with as little reverence as any other. It would seem that Nebuchadnezzar had some respect for these vessels, as having been employed in the purposes of religion; at least so much respect as to lay them up as trophies of victory, and that this respect had been shown for them under the reign of his successors, until the exciting scenes of this “impious feast” occurred, when all veneration for them vanished. It was not very common for females in the East to be present at such festivals as this, but it would seem that all the usual restraints of propriety and decency came to be disregarded as the feast advanced. The “wives and concubines” were probably not present when the feast began, for it was made for “his lords” Daniel 5:1; but when the scenes of revelry had advanced so far that it was proposed to introduce the sacred vessels of the temple, it would not be unnatural to propose also to introduce the females of the court.
A similar instance is related in the book of Esther. In the feast which Ahasuerus gave, it is said that “on the seventh day, when the heart of the king was merry with wine, he commanded Mehuman, Biztha, etc., the seven chamberlains that served in the presence of Ahasuerus the king, to bring Vashti the queen before the king with the crown royal, to show the people and the princes her beauty,” etc. Esther 1:10-11. Compare Joseph. “Ant.” b. xi. ch. 6: Section 1. The females that were thus introduced to the banquet were those of the harem, yet it would seem that she who was usually called “the queen” by way of eminence, or the queen-mother (compare the note at Esther 5:10), was not among them at this time. The females in the court of an Oriental monarch were divided into two classes; those who were properly concubines, and who had none of the privileges of a wife; and those of a higher class, and who were spoken of as wives, and to whom pertained the privileges of that relation. Among the latter, also, in the court of a king, it would seem that there was one to whom properly belonged the appellation of “queen;” that is, probably, a favorite wife whose children were heirs to the crown. See Bertholdt, in loc. Compare 2 Samuel 5:13; 1 Kings 11:3; Sol 6:8.