(Isa. 13:17)
The Medes … came from Persia and easily conquered Babylon in 538 b.c. The walls were destroyed twenty years later, after which the city never again became the capital of an independent, strong Mesopotamian power. Two centuries later, after the Greeks, under Alexander the Great, conquered the Persians, Babylon rapidly declined in commercial and cultural importance as Seleucia became the major city in the area. By the time of Christ, only a few astronomers and mathematicians continued to live in the ancient, sparsely populated city. After they left, Babylon became a deserted tell (mound), which sand and brush gradually covered until it became a hill used only by wild animals and as grazing land for nomadic flocks
(Victor L. Ludlow, Isaiah: Prophet, Seer, and Poet [Salt Lake City: Deseret Book Co., 1982], 185.)
God used Assyria as a rod to destroy many ancient Near East peoples; now he uses the wickedness of the Medes to kill each other (the Medes were located in the mountainous region north and east of Babylon) …
Historically, the Medes, having formed an alliance with the Persians under Cyrus the Great’s leadership, conquered the great Babylonian empire by damming the Euphrates River, marching through its riverbed, going under the city walls, and subsequently capturing Babylon. This event took place more than one hundred sixty years after Isaiah’s prophecy. The phrase shall not regard silver and gold indicates that the Medes did not go into battle to obtain plunder (silver and gold); instead, their motivation was to kill, and gain power and control. Perhaps ancient Media points forward to all nations of the last days who have the same wicked designs.
(Donald W. Parry, Jay A. Parry, and Tina M. Peterson, Understanding Isaiah [Salt Lake City: Deseret Book Co., 1998], 137–38.)
The man who led the Medes and the confederation of nearby nations against Babylon turned out to be Cyrus. His mother was the daughter of the king of the Medes, and according to tradition the old king was so cruel to his people that Cyrus rose up and overthrew him. Cyrus was supported by the Persians. He combined the two peoples. He also conquered all of the tributaries of the old Assyrian empire and formed many of them into a confederation before attacking Babylon in 539 b.c. Cyrus was not a cruel or brutal king, but generous with his subjects and wise in his administration of their affairs. The Lord therefore blessed him with success in putting down the wickedness of Babylon. It was not Cyrus, but subsequent Persian kings, who fulfilled Isaiah’s prophecies concerning the total devastation of Babylon.
(W. Cleon Skousen, Isaiah Speaks to Modern Times [Salt Lake City: Ensign Publishing Co., 1984], 269.)