Thus says the Lord:
r“Behold, a people is coming sfrom the north country,
a great nation is stirring from tthe farthest parts of the earth.
23 They lay hold on bow and javelin;
they are ucruel and have no mercy;
vthe sound of them is like the roaring sea;
they ride on horses,
set in array as a man for battle,
against you, O daughter of Zion!”
Verse 23 is the reference for Foreign Spearmen, and yet he has no identifiers, but it seems to me that this verse is referring to the Babylonian invasion (from the north), which is kind of what Jeremiah's whole prophecy was about. "Jerusalem's gonna burn!" ...and the Babylonians did that.
So yeah, Foreign Spearmen for Babylonian Spearmen. Kinda defeats the name, but hey, Babylon was still foreign to them.