But, within this series of diffuse attachments, his most binding and most frequently mobilized loyalty is to his 'diya-paying group'. This unit, with a fighting strength of from a few hundred to a few thousand men, consists of close kinsmen united by a specific contractual alliance whose terms stipulate that they should pay and receive blood-compensation (Arabic, diya) in concert. An injury done by or to any member of the group implicates all those who are a party to its treaty. Thus if a man of one group is killed by a man of another, the first group will collectively claim the damages due from the second.

I.M. Lewis, I. M. Lewis, A Modern History of the Som…, loc. 68