TIMBUKTU, Mali – 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-Qaida 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.

“It’s the first time someone has bought such a large amount,” said the mat seller, Leitny Cisse al-Djoumat. “They didn’t explain why they wanted so many.”