The Gadianton robbers were a secret band of murderers and thieves active among the Nephites and Lamanites from about 50 B.C. until the end of the Nephite nation. The band was first formed by Kishkumen; after Kishkumen was killed, Gadianton, a man expert in flattery and in the craft of secret murder and robbery, became its leader around 52 B.C. and gave the band his name (Helaman 2:4-5). Members bound themselves by oaths and covenants to murder, rob, and gain power, and the band grew in numbers among both peoples, most of all among the more wicked Lamanites (Helaman 6:18). The Book of Mormon is explicit that these secret oaths did not come from ancient records but were placed directly into Gadianton’s heart by the same being who tempted Adam and Eve, plotted with Cain, and has carried these works of darkness forward from generation to generation — he who is the author of all sin (Helaman 6:26-30).
The band’s strength rose and fell. At one point the Nephites swept it away until it became extinct and its secret plans were hidden in the earth, only to be revived later (Helaman 11:10). The robbers held strongholds in the mountains, and their secret places were so strong that the people could not overpower them; from these holds they committed many murders (3 Nephi 1:27).
The band gained the sole management of the Nephite government, using its power to oppress the poor, the meek, and the humble followers of God (Helaman 6:39). The robbers came to an end at the time of the destruction that accompanied the death of Jesus Christ, when cities given to secret murders and combinations, such as Jacobugath, were burned (3 Nephi 9:9).
The secret oaths and combinations of Gadianton were built up again in the third century A.D., after the long period of peace following Christ’s visit ended, and by 300 years the robbers had spread over all the land (4 Nephi 1:42-46). They continued to the end of the Nephite record; the Nephites fought them and made a treaty dividing the land with the Lamanites and the robbers of Gadianton in the 350th year (Mormon 2:27-28). Mormon wrote that Gadianton “did prove the overthrow, yea, almost the entire destruction of the people of Nephi” (Helaman 2:13). Moroni, drawing on the Jaredite record, warned future readers that any nation that upholds such secret combinations to get power and gain shall be destroyed, for they are built up by the devil, the father of all lies, and those who encounter them are commanded to awake to their awful situation (Ether 8:22-25).