The people of Zemnarihah were the Gadianton robbers who, in the twenty-first year, laid siege to the Nephites under Zemnarihah, the leader they had appointed (3 Nephi 4:17). Rather than give battle, they surrounded the Nephites on every side to cut them off from their lands and provisions and force their surrender. The siege failed: the Nephites had stored up provisions, while the robbers, living only on game they hunted in the wilderness, began to starve as the wild game grew scarce. Nephite armies marched out by day and night and cut the robbers off by the thousands, until the people of Zemnarihah wished to withdraw (3 Nephi 4:18-22).
Zemnarihah ordered his people to leave the siege and march into the furthermost parts of the land northward (3 Nephi 4:23). The Nephite commander Gidgiddoni, aware of their plan and their weakness from hunger, sent his armies out at night to cut off the line of retreat, so the robbers were met both in front and rear (3 Nephi 4:24-26). Many thousands yielded themselves up as prisoners, and the remainder were slain (3 Nephi 4:27).