The city of Gideon was a Nephite settlement east of the river Sidon, in the valley of Gideon within the land of Gideon. Both city and valley were named after Gideon, who opposed King Noah and was killed with the sword by Nehor (Alma 2:20). The valley first appears when Alma the Younger, unable to pursue the fleeing Amlicites further, halted his army there for the night, near enough to Zarahemla that his people returned to the city the next day (Alma 2:20).
After giving up the judgment-seat to Nephihah, Alma went east over the river Sidon into the valley of Gideon, where a city had been built and a church already established. He preached to the people there on the coming of Christ and the Son of God who would redeem his people, then returned to Zarahemla, around 83 B.C. (Alma 6:7–8:10).
Korihor was carried into the land of Gideon and tried to preach there, but had little success and was bound and brought before the high priest Giddonah and the chief judge of the land (Alma 30:21, 23). During the rule of the king-men, the chief judge Pahoran, driven out of Zarahemla, fled to the land of Gideon and called on Captain Moroni for help; Moroni marched there, gathered forces along the way, united his army with Pahoran’s, and the two went down together to retake Zarahemla from Pachus and the dissenters (Alma 61:5, 15; 62:3-7).
Samuel the Lamanite pronounced a woe on the city of Gideon for its wickedness, around 6 B.C. (Hel. 13:15).