One of the last things the bearded fighters did before leaving this city was to drive to the market where traders lay their carpets out in the sand.

The al-Qaeda extremists bypassed the brightly colored, high-end synthetic floor coverings and stopped their pickup truck in front of a man selling more modest mats woven from desert grass, priced at $1.40 apiece. There they bought two bales of 25 mats each, and asked him to bundle them on top of the car, along with a stack of sticks.