Rouran Khaganate
The Hephthalites were originally vassals of the Rouran Khaganate but split from their overlords in the early fifth century. The next time they were mentioned was in Persian sources as foes of Yazdegerd II (435–457), who from 442, fought 'tribes of the Hephthalites', according to the Armenian Elisee Vardaped.