In January 2002, Rory Stewart walked across Afghanistan-surviving by his wits, his knowledge of Persian dialects and Muslim customs, and the kindness of strangers. By day he passed through mountains covered in nine feet of snow, hamlets burned and emptied by the Taliban, and communities thriving amid the remains of medieval civilizations. By night he slept on villagers" floors, shared their meals, and listened to their stories of the recent and ancient...