In 20 B.C.there was widespread warfare throughout the land, particularly among the people of Nephi. Here is the way the scriptures describe it.
This means that the Nephites were killing off each other in fratricidal warfare for three solid years. However, Nephi realized that the principal source of all this killing was the Gadianton secret band of robbers.
Now Helaman felt the Nephites had tolerated as much bloodshed as he could endure. Therefore he cried out to the Lord.