John Calvin on Jeremiah 51:28

He now repeats what he had said of preparing the nations; but he mentions them first generally, and then he comes to specify them particularly. He then bids the nations to be sent for, and then he shows who they were, even the kingdoms of the Medes The Hebrew is, “the kings of Media;” but the Sept. and Syr. have “the king of Media;” which is required by “his dominion” at the end of the verse: the pronoun affixed to “captains” and “rulers” is “her,” referring to Media. — Ed. There was, indeed, but one kingdom, but many kings were subject to it. Then, on account of the many provinces over which satraps ruled, and also on account of many tributary countries, the Prophet was not satisfied to use the singular number, but calls them in the plural number, the kingdoms of the Medes; for that monarchy had extended itself far and wide, so that many kings were subject to Darius.

And it tended, in no small degree, to show the certainty of this prophecy, that Jeremiah declared, before Cyrus or even Darius was born, that the Medes would come. But we have stated, that though Cyrus, being singularly active and a good warrior, carried on the war, yet Darius was the first in authority. Then Babylon obeyed the Medes for a time; but as Darius was now old, Cyrus succeeded him; and then the monarchy was transferred to Persia; and laws issued thence until the time of Alexander the Great, who, together with his catamite, burnt the tower. Nor is there a doubt but that many memorable transactions were deposited there. But Alexander being drunk, seized a torch and burnt the tower; for he thought that the memory of the Oriental monarchy could thus be abolished.

We now then perceive why the Prophet expressly mentions here the Medes; and he adds, the captains and princes He includes, no doubt, under these names, all the satraps and kings. At length he adds, the whole land of its dominion, or jurisdiction; and by this word he designates the kingdoms already mentioned. It now follows, —

Jeremiah 51:29

29. And the land shall tremble and sorrow: for every purpose of the LORD shall be performed against Babylon, to make the land of Babylon a desolation without an inhabitant.

29. Et contremuit terra, et doluit (similitudo sumpta est a parturientibus,) quia stabilita fuit super Babylon cogitationes (in plurali numero ponit cum tamen verbum sit singulare, hoc est, stabilitae sunt cogitationes) Jehovae ad ponendum terram Babylonis in solitudinem, ita ut non sit habitator (vel, qui illic habitet.)