There appears to be some confusion about the term in the late Roman period, as armored cavalrymen of any sort that were traditionally referred to as in the Republican period later became exclusively designated as "cataphracts". Vegetius, writing in the fourth century, described armor of any sort as "cataphracts" – which at the time of writing would have been either or . Ammianus Marcellinus, Roman soldier and historian of the fourth century, mentions the "" – the "cataphract cavalry which they regularly call clibanarii" (implying that clibanarii is a foreign term, not used in Classical Latin).