The East Wilderness was a region east of the land of Zarahemla, reaching to the seashore, that formed part of the frontier between Nephite and Lamanite territory.
After the death of Amulon, the surviving priests of Amulon’s seed fled into the east wilderness and usurped power and authority over the Lamanites, causing many Lamanites to be put to death by fire for their belief (Alma 25:5). The killings stirred up other Lamanites to anger, and as contention spread they hunted the seed of Amulon and his brethren, who fled into the east wilderness (Alma 25:8).
Captain Moroni later sent his armies into the east wilderness and drove the Lamanites there back into their own lands south of Zarahemla (Alma 50:7). He then directed inhabitants of Zarahemla and the surrounding land to move into the cleared territory, extending settlement to the borders by the seashore (Alma 50:9). Moroni cut off the Lamanite strongholds in the east wilderness and on the west, fortifying the line between the Nephites and the Lamanites from the west sea by the head of the river Sidon (Alma 50:11).
In a later campaign Moroni, with Lehi and Teancum, encamped around the borders of the land of Moroni and encircled the Lamanites, with the wilderness on the south and on the east (Alma 62:34).