Who was left from Midyan? Yisrael killed out Midyan 220 years ago, leaving only infant girls for slaves (Bamidbar 31:17,18). Lineage of Nochrim follows the father!
This was the Midyan to which Moshe fled; it is near Har Sinai and Egypt (PF). Bamidbar Rabah 22:4 - some say that Yisrael destroyed a different Midyan 1 , near Mo'av; it is desolate to this day.
Yisrael killed all the Midyanim living in Midyan. Midyanim living elsewhere at the time survived, e.g. Yisro and Balak 2 . (PF)
Kli Yakar (Lani'ado) was unsure if this is the same Midyan from the days of Moshe. (Perhaps after Yisrael destroyed Midyan, others came and settled there; they are called Midyan because they lived there. -PF)
This is unlike the opinion there that Moshe did not lead the war, lest he destroy the place where he grew up.
Rashi (Bamidbar 22:4): Balak was a noble of Midyan; Mo'av appointed him to be their king.
What are Minharos?
Rashi: They are hollows in rocks.
Radak, Malbim #1: They are caves with holes for light to enter.
Malbim #2: They are torches to light on the mountains when the enemy comes, so they can save their possessions.
What are Metzados?
Rashi: They are bridges.
