Heshbon. See on ch. 48:2. The Moabite city is called upon to lament what has already happened to Ai, perhaps because it forebodes her doom also.
Ai. This is the only reference to an Ai in Transjordan. The town was probably near Heshbon.
Hedges. Heb. gederoth, a word used elsewhere of sheepfolds (see Num. 32:16, 36; 1 Sam. 24:3; Zeph. 2:6), which were fenced enclosures in the open fields. Jeremiah’s thought here is evidently that the people of Ammon will forsake their conquered cities and seek refuge in the open country in these corrals.
Their king. Or, Milcom (see on v. 1).