Here the prophet declares those particular princes and nations that should be God's instruments to destroy Babylon, viz. Cyrus and Darius, the emperors of the Medes, with all the forces under their command, and people under their dominion.
Related Commentaries of Jeremiah 51:28
Jeremiah 51:28
28 Prepare against her the nations with the kings of the Medes, the captains thereof, and all the rulers thereof, and all the land of his dominion.