Afternoon prayers were done, and Ahmed Felaifel lay down in the sand in the midday heat beneath a canopy resting on cinder-block walls. He was emotionally exhausted. His eldest son had been killed by the police a few days earlier, and he could barely find the energy to explain why he had disowned his two sons five years ago, in a tribal sentence of last resort called tashmees, which literally means "to be put out to the sun."

"They grew beards, they grew beards," he finally said, a flash of anger slicing through his weariness. In this region, that is shorthand for only one thing: the Felaifel brothers became religious extremists...

...El Arish is effectively the capital of northern Sinai, the biggest city center in the area with a population of about 120,000, 240 miles northeast of Cairo. Most of its citizens work for the government, farm or herd animals in the desert, or are unemployed. The city has miles of Mediterranean beachfront with signs directing bathers to places like Coral Cove. But the town never caught on as a tourist attraction, either for foreigners or Egyptians.

El Arish, just 35 miles from Rafa, which borders Israel, did, however, develop a strong pro-Palestinian movement. Residents have helped smuggle weapons and other supplies into Gaza, according to local officials.

For so poor a place, there is a tremendous amount of construction, house after house going up. There are also new, privately financed mosques every few blocks. A local political leader said that one of the new mosques also ran a health clinic supported by money from "the gulf." He did not specify further...