Persian cataphracts were a contiguous division known as the "Savaran" (Persian: "سواران", literally meaning "riders") during the era of the Sassanid army and remained a formidable force from the 3rd to 7th centuries until the collapse of the Sassanid Empire. Initially the Sassanid dynasty continued the cavalry traditions of the Parthians, fielding units of super-heavy cavalry. This gradually fell out of favour, and a "universal" cavalryman was developed during the later 3rd century, able to fight as a mounted archer as well as a cataphract. This was perhaps in response to the harassing, nomadic combat style used by the Sassanids' northern neighbours who frequently raided their borders, such as the Huns, Hephthalites, Xiongnu, Scythians, and Kushans, all of which favoured hit and run tactics and relied almost solely upon horse archers for combat. However, as the Roman-Persian wars intensified to the West, sweeping military reforms were again re-established. During the 4th century, Shapur II of Persia attempted to reinstate the super-heavy cataphracts of previous Persian dynasties to counter the formation of the new, Roman Comitatenses, the dedicated, front-line legionaries who were the heavy infantry of the late Roman Empire. The elite of the Persian cataphracts, known as the Pushtigban Body Guards, were sourced from the very best of the "Savaran" divisions and were akin in their deployment and military role to their Roman counterparts, the Praetorian Guard, used exclusively by Roman emperors. Ammianus Marcellinus remarked in his memoirs that members of the Pushtigban were able to impale two Roman soldiers on their spears at once with a single furious charge. Persian cataphract archery also seems to have been again revived in late antiquity, perhaps as a response (or even a stimulus) to an emerging trend of the late Roman army towards mobility and versatility in their means of warfare.