A nation sprung from Ben-ammi, Lot's son by his younger daughter (Genesis 19:38; Psalm 83:7-8), as Moab by his elder, after Lot escaped from Sodom. Ammon and Moab appear continually together; both are said to have hired Balaam (Deuteronomy 13:4), though Moab alone is mentioned in the detailed account (Numbers 22; 23). The land from Arnon river to Jabbok is assigned to both (Judges 11:12-18; Judges 11:25). The Israelites dispossessed the Amorites of land which afterward Ammon occupied, between Arnon and Jabbok, but did not, as Jephthah reasons, dispossess Ammon of it, though now claiming it as theirs (Numbers 21:24; Numbers 21:26; Numbers 21:29). Ammon destroyed the aboriginal Rephaim or giants, named Zamzummim, and occupied their land, Jabbok being their boundary (Deuteronomy 2:20-21; Deuteronomy 2:37).
Moab was probably the more civilized half of Lot's descendants; whence we read of the plentiful fields, hay, summer fruits, vineyards, presses, songs of the grape treaders, of Moab (Isaiah 15; 16; Jeremiah 48): Ammon the more fierce, plundering, Bedouin-like half; whence we read of their threat of thrusting out the right eye of all in Jabesh Gilead (1 Samuel 11:2), ripping up pregnant women in Gilead (Amos 1:13), treacherously murdering, as Ishmael, Baalis' agent, did (Jeremiah 40:14; Jeremiah 41:5-7), suspecting and insulting their ally David to their own ruin (2 Samuel 10:1-5; 2 Samuel 12:31). Ammon's one stronghold, Rabbah, "the city of: waters" (20 cities are mentioned Judges 11:33, perhaps some Moabite cities), forms a contrast to Moab's numerous towns with their "high places" (Jeremiah 48); their idol, Moloch, accordingly they worshipped in a tent, the token of nomad life, not a fixed temple or high place, such as was appropriated to the god of the more settled people Moab (Amos 5:26; Acts 7:43).
They crossed Jordan and seized Jericho for a time (Judges 3:13). Chephar-ha-Ammonai (the hamlet of the Ammonites), in Benjamin, at the head of the passes from the Jordan westward, marks their having temporarily been in that region. Their unwillingness to help Israel, and their joining Moab in hiring Balaam (Deuteronomy 23:2; Deuteronomy 23:46; Nehemiah 13:2), caused their exclusion (like that of a bastard) from the Lord's congregation for ten generations; whereas Edom, who had not hired him, was only excluded for three. The exclusion was from full Israelite citizenship, not from the spiritual privileges of the covenant, if they became proselytes. Previously to David, Jephthah and Saul had sorely punished them (Judges 11:33; 1 Samuel 11:11; 1 Samuel 14:47).
Ammon joined with Moab in the expedition for uprooting Judah from its possession, in Jehoshaphat's reign (2 Chronicles 20; Psalm 83:3-7). So utterly were the confederates routed that the Jews spent three days in gathering the spoil. They had to bring gifts to Uzziah (2 Chronicles 26:8). Jotham reduced them to pay 100 talents of silver, 10,000 measures of wheat, and 10,000 of barley. Ammon seized on the cities of Gad from which Tiglath Pileser had carried the Israelites (Jeremiah 49:1-6; Zephaniah 2:8-9). On the return from Jerusalem Tobiah, an Ammonite, joined with Sanballat, of Horonaim of Moab, in opposing Nehemiah's restoration of the city walls (Nehemiah 2:10; Nehemiah 2:19).
Naamah, Solomon's wife, mother of Rehoboam, was an Ammonite. Their idol, Moloch, appears also under the varied form Milcom and Malcham, as the Hebrew for "their king" may be rendered. Compare Zephaniah 1:5; 2 Samuel 12:30. Solomon's Ammonite wives seduced him to rear an altar to this "abomination," to his own hurt (Jeremiah 49:1; Jeremiah 49:3). Nahash, perhaps a common title of their kings, means a serpent. Shobi, the son of David's friend, followed his father's rather than Hanun his brother's steps, showing kindness to David in adversity (2 Samuel 17:27).