A short paper (44 pgs) by a British academic who has spent years in the Yemen and published by a US think tank (POMED) on a fascinating aspect of the multiple conflicts in the Yemen.

A "taster" from the summary:
Some Western observers (along with many Yemeni government authorities) contend that a key reason for AQAP’s staying-power is that some tribes are aligned with the terrorist group and provide it with safe havens, fighters, and other support. To be sure, AQAP has a presence in some tribal areas, and some tribal members (along with other Yemenis, and some foreigners) have joined the group. But in doing so, they have acted independently, against the wishes of their tribes. Yemeni tribes as collective entities —as opposed to individual tribesmen—have not allied with AQAP or agreed to give its fighters sanctuary. Tribes reject the group’s radical and violent ideology and tend to see AQAP as a serious challenge to their authority.

Because of tribal pushback, AQAP has only been able to seize territory and make other gains in parts of Yemen where the tribal structure is relatively weak. The failure of the Yemeni ruling elite to seriously confront the AQAP problem, and the civil war instigated by that same ruling elite, have been more significant factors in the group’s spread than any tribal action.
Link:http://pomed.org/wp-content/uploads/...NAL_180201.pdf