Albert Barnes Commentary Jeremiah 8:16

"The snorting of his horses is heard from Dan: at the sound of the neighing of his strong ones the whole land trembleth; for they are come, and have devoured the land and all that is in it; the city and those that dwell therein." — Jeremiah 8:16 (ASV)

Dan — that is, the northern boundary of the land.

His strong ones — that is, “his war-horses.”