Behold, a people shall come from the north Namely, the Medes; and a great nation That is, who are a great nation; for this is no more than an explicative of the foregoing sentence. And many kings Namely, the kings of the Persians, Armenians, Hyrcanians, Cadusians, and others who fought under Cyrus's banner, as allies or friends to him. Their voice shall roar like the sea The noise of an army is fitly compared to the roaring of the sea when it rages and is tempestuous. Every one put in array In exact and firm order, as if the whole host were but one man. The king of Babylon hath heard, &c. Belshazzar was of himself a weak and dissolute prince, and was soon routed in the field; and so dismayed that he shut himself up in Babylon. Behold, he shall come up like a lion See notes on Jeremiah 49:19-21, where we have applied unto Edom what is here spoken against Babylon. At the noise of the taking of Babylon the earth is moved, and the cry is heard, &c. These words are intended to express the greatness of the destruction of Babylon, which should be such as should make all that part of the world to shake and tremble; and the nations, whether near or far remote, should be astonished at the downfall of so great a city and potent an empire.
Jeremiah 50:41-46
41 Behold, a people shall come from the north, and a great nation, and many kings shall be raised up from the coasts of the earth.
42 They shall hold the bow and the lance: they are cruel, and will not shew mercy: their voice shall roar like the sea, and they shall ride upon horses, every one put in array, like a man to the battle, against thee, O daughter of Babylon.
43 The king of Babylon hath heard the report of them, and his hands waxed feeble: anguish took hold of him, and pangs as of a woman in travail.
44 Behold, he shall come up like a lion from the swelling of Jordan unto the habitation of the strong: but I will make them suddenly run away from her: and who is a chosen man, that I may appoint over her? for who is like me? and who will appoint me the time? and who is that shepherd that will stand before me?
45 Therefore hear ye the counsel of the LORD, that he hath taken against Babylon; and his purposes, that he hath purposed against the land of the Chaldeans: Surely the least of the flock shall draw them out: surely he shall make their habitation desolate with them.
46 At the noise of the taking of Babylon the earth is moved, and the cry is heard among the nations.