Ammon in Fausset's Bible Dictionary

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...

Link: https://bible-history.com/faussets/A/Ammon/