Every closed factory has its own kind of unbearable silence. The Yazegi Group's soft-drink plant in Gaza, with its maze of metal tubes and conveyor belts all switched off, has the hush of a futuristic mausoleum. Marketing manager Ammar Yazegi pauses beside empty 7Up bottles stacked in perfect emerald-green cubes up to the rafters and says, "I miss the music of the machines and workers. It's a beautiful noise. This silence drives me crazy."
His family misses another sound: the ka-ching! of money. For years the Yazegi Group had a captive market of 1.48 million Palestinians living in the narrow coastal...