T he Iranian Empire encountered an unfamiliar kind of Hun on its northeastern frontiers in the latter half of the fourth century. Migrating from the steppes south of the Altai Mountains as heirs of the Xiongnu imperial tradition, these Huns came not to raid but to rule. 1 If some nomadic warriors sought positions as mercenaries in the service ofthe king ofkings, others took control ofBalkh and Kabul, once strongholds ofthe Iranian Empire, as well as Sogdian cities such as Samarkand, Bukhara, and Chach just beyond its former limits. 2 With few geographical barriers to prevent nomadic armies from entering the Iranian plateau, the heart ofthe empire was now exposed to the steppe. 3 Unlike the more famous armies ofAttila that the Romans encountered, the Huns in Central Asia combined the best of steppe and sedentary state structures, adapting the administrative and ideological institutions