Alma 6:7

And now it came to pass that when Alma had made these regulations, he departed from them, yea, from the church which was in the city of Zarahemla, and went over upon the east of the river Sidon, into the valley of Gideon, there having been a city built which was called the city of Gideon, which was in the valley that was called Gideon, being called after the man which was slain by the hand of Nehor with the sword.

After Alma made these rules, he left them. He left the church in the city of Zarahemla. He went east across the river Sidon to the valley of Gideon. A city had been built there called the city of Gideon. It was in the valley of Gideon. The valley was named after the man named Gideon. He was killed by Nehor with a sword.

Once Alma had set up these guidelines, he left the church in Zarahemla and traveled east across the Sidon River to the valley of Gideon. There was a city there also called Gideon, named after the man Nehor had killed with a sword.