Behold, I will stir up the Medes against them. Isaiah's knowledge that the Medes should take a leading part in the destruction of Babylon is, no doubt, as surprising a fact as almost any other in the entire range of prophetic foresight, or insight, as set before us in Scripture.
The Medes were known to Moses as an ancient nation of some importance (Genesis 10:2); but since his time had been unmentioned by any sacred writer; and, as a living nation, had only just come within the range of Israelite vision, by the fact that, when Sargon deported the Samaritans from Samaria, he placed some of them "in the cities of the Medes" (2 Kings 17:6).
The Assyrians had become acquainted with them somewhat more than a century earlier, and had made frequent incursions into their country, finding them a weak and divided people, under the government of a large number of petty chiefs.
Sargon had conquered a portion of the tribes, and placed prefects in the cities; at the same time planting colonists in them from other parts of the empire. That, when the weakness of Media was being thus made apparent, Isaiah should have foreseen its coming greatness can only be accounted for by his having received a Divine communication on the subject.
Subsequently, he had a still more exact and complete communication (Isaiah 21:2). Which shall not regard silver. The Medes were not a particularly disinterested people; but in the attack on Babylon, made by Cyrus, the object was not plunder, but conquest and the extension of dominion.
The main treasures of Babylon—those in the great temple of Bolus—were not carried off by Cyrus, as appears both from his own inscriptions, and from Herodotus.