31  And they were again obliged to return out of the wilderness and out of the ^amountains unto their own lands, because of the exceeding greatness of the numbers of those robbers who infested the mountains and the wilderness.

  11  And it came to pass in the thirteenth year there began to be wars and contentions throughout all the land; for the ^aGadianton robbers had become so numerous, and did slay so many of the people, and did lay waste so many cities, and did spread so much death and carnage throughout the land, that it became expedient that all the people, both the Nephites and the Lamanites, should take up arms against them.