The Great Wall in its currently recognizable form was largely built during the short-lived Ch’in dynasty (221-206 b c e ). It did not bring the pres­ sures of the Hsiung-nu to an end but it made it easier for China to respond to them in its own fashion. The importance of the wall was proved during the 2nd century b c e when the Chinese tried to bring the Hsiung-nu to bay. Huge punitive expeditions would march north of the wall only to find that the nomads melted away; when the Chinese retreated behind their wall the raids were renewed.