During the Second Long Interval, five weyrs (Fort, High Reaches, Igen, Ista, and Telgar) were empty. All the inhabitants, Dragons, Riders, and support staff, had mysteriously vanished shortly after the end of the Eighth Pass. At the time, this came as a major shock to the rest of Pern. No one could figure out why every last person and dragon in those five weyrs had disappeared, nor why Benden had been spared whatever unknown calamity struck the other five.