 The history of <unk> 's reign is problematic in that no historical sources survived that were contemporary with <unk> . These first histories at one time did exist and were described as biased and <unk> , either overly critical or praising of <unk> . The original sources were also said to contradict on a number of events . Nonetheless , these lost primary sources were the basis of surviving secondary and tertiary histories on <unk> written by the next generations of historians . A few of the contemporary historians are known by name . <unk> <unk> , <unk> Rufus and Pliny the Elder all wrote condemning histories on <unk> that are now lost . There were also pro @-@ <unk> histories , but it is unknown who wrote them or for what <unk> <unk> was praised . 
