Albert Barnes Commentary Judges 3:13

"And he gathered unto him the children of Ammon and Amalek; and he went and smote Israel, and they possessed the city of palm-trees." — Judges 3:13 (ASV)

The children of Ammon (Bent-Ammon), almost always so spoken of from their ancestor Ben-ammi (Genesis 19:38), seem to be under the leadership of the king of Moab, as are also the Amalekites; this is perhaps the strengthening spoken of in Judges 3:12. In Judges 6:0, the combination is Midianites, Amalekites, and children of the East, or Arab tribes. In the narrative of Jephthah’s judgeship, the Ammonites alone are mentioned, but with a reference to the Moabites, and as if they were one people (Judges 11:24).

The Amalekites appear as the constant and bitter foes of the Israelites (Exodus 17:8, see notes and references); and the naming of a mountain in Ephraim, “the mount of the Amalekites” (Judges 12:15), is probably a memorial of this joint invasion of Moabites and Amalekites and marks the scene either of their occupation or of some signal victory over them.

The city of palm trees, that is, Jericho (Judges 1:16), had been utterly destroyed by Joshua and was not rebuilt until the time of Ahab (Joshua 6:24–26; 1 Kings 16:34). Consequently, it can only have existed at this time as an unwalled village. This state is comparable to Jerusalem after its destruction by Nebuzaradan, before Nehemiah rebuilt its walls, and also to its modern representative er-Riha, a village with a fortress for the Turkish garrison.

This occupation of Jericho should be compared with the invasion in Judges 10:9, where two out of the three tribes named, Benjamin and Ephraim, are the same as those here concerned, and where (Judges 10:7) the Philistines are coupled with the Ammonites, just as here (Judges 3:31) the Philistines are mentioned in near connection with the Moabites.

See Introduction.