Albert Barnes Commentary Jeremiah 51:4

"And they shall fall down slain in the land of the Chaldeans, and thrust through in her streets." — Jeremiah 51:4 (ASV)

Translate it: And they, that is, the young men who form her host (Jeremiah 51:3), shall fall slain in the land of the Chaldaeans, and pierced through in her streets, that is, the streets of Babylon.