The Sidon River was the principal river of the Nephite lands, originating near the south wilderness and the land of Manti and running by the land of Zarahemla, which lay on its west (Alma 2:15). The original description gives its course as flowing northward past the eastern boundary of Zarahemla and reaching the sea, a span exceeding two hundred miles in a tropical zone; such a length would carry a considerable volume of water and likely form a delta at the coast.
Battles between Nephites, Amlicites, and Lamanites were fought along the river. When the Amlicites came upon the hill Amnihu east of Sidon to war on the Nephites, Alma’s army drove them and the Lamanites back across the river; Alma cleared the bank on the west of Sidon by throwing the slain Lamanites into the water so his people could cross and fight on the west side (Alma 2:34). It later figured in Moroni’s defense of the east wilderness, where he drove out the Lamanites, settled the land to the seashore, and built fortifications (Alma 50:7, 9–11).
Under Alma, who had been consecrated high priest over the church, many were baptized in the waters of Sidon as the church was established more fully (Alma 4:4).
The label “land of Zarahemla” came to cover a larger expanse around the Sidon River. From the local vicinity of the city of Zarahemla it expanded to include territory reaching the east sea (Alma 50:7, 11).