The disunited Kushan and Sasanian kingdoms were in a poor position to meet the threat several waves of Xionite/Huna invaders from the north from the 4th century onwards. In particular, the Hephthalites (or "Ebodalo"; Bactrian script ηβοδαλο) swept out of Central Asia during the 5th century into Bactria and Iran, overwhelming the last of the Kushan kingdoms. Historians believe that Hephthalite control continued for a century and was marked by constant warfare with the Sassanians to the west who exerted nominal control over the region.