Part of our world for ages lived on aggressive looting but not cultivation or business.
I have read Baburnama - autobiography of Babur - by culture the values they held as profession to earn living, to organize strike force and loot. The loot is not only food and grains, moveable assets but women too and children as Slaves.
It started with Genghis Khan who showed the way, and was reasonably successful in dominating half of the world for about 250 years.
They are born in that culture. Only binding force for such group formation is faith and religion as it is practiced by the group.
One must learn to live with them and be aware that their lifetime is at most 10 to 50 years. The region is quite vast starting with egypt Africa middle east and a substantial part of Asia. Unsurprisingly the religion practiced ..... that equates violence is the means of reaching God by that the right to be unaccountable.
It is best that they are kept on isolation since they can't ever be part of long lived civilization. They do not produce but consume.
It is not so very difficult to eliminate the leader but it is useless to do that. The group is not going to change their ways nor you can contain them in prison.
We must learn our lesson from Taliban Libya Egypt - only strategy worthwhile to pursue is to keep them rounded up in small territory in isolation.
Iraq is a failed state, so is Syria, so is many. Let them loot themselves and not loot rest of the world.
We must isolate them with a Wall - we must not to get involved under no circumstances. This wall must have no gate or channel for communication. Give them freedom to whatever they want. The wall must have written everywhere crossing it sure death by electrocution poison gas and contagious skin disease HIV and they should stay away. Create herbs around the wall moats beyond it and blare microphone of horror stories of what the living hell it is beyond the wall.
All bees have a sting. All barbarian has an AK47 assault Machine gun. Let them manufacture that as many they want but do not supply them one or manufacturing material for creating one as well as gunpowder.
We must guard civilization and refrain from creating one out of them instead we must keep them in isolation.
I recommend reading of Baburnama he was anephew of Taimulang he had language gift of Taimur - he bares his mind.