 Due to the lack of written sources on this period , much of Nerva 's life has remained obscure . The most substantial surviving account of the reign of Nerva was written by the 3rd @-@ century historian Cassius Dio . His Roman History , which spans nearly a millennium , from the arrival of Aeneas in Italy until the year 229 , was composed more than one hundred years after Nerva had died . Further details are added by an abridged biography from the Epitome de Caesaribus , a work alleged to have been authored by the 4th @-@ century historian Aurelius Victor . 
 Due to the lack of written sources on this period , much of Nerva <a href='null_genetive' title='1'><mark>'s</mark></a>life <a href='been_done' title='2'><mark>has</mark></a> remained obscure . The most substantial surviving account of the reign of Nerva was written by the 3rd @-@ century historian Cassius Dio . His Roman History , which <a href='uninflect' title='3'><mark>spans</mark></a> nearly a millennium , from the arrival of Aeneas in Italy until the year 229 , was composed more than one hundred years after Nerva <a href='been_done' title='4'><mark>had</mark></a> died . Further details are added by an abridged biography from the Epitome de Caesaribus , a work alleged to <a href='been_done' title='5'><mark>have</mark></a> been authored by the 4th @-@ century historian Aurelius Victor . 
Due to the lack of written sources on this period , much of Nerva  life done remained obscure . The most substantial surviving account of da reign of Nerva was written by the 3rd @-@ century historian Cassius Dio . His Roman History , which span nearly a millennium , from the arrival of Aeneas in Italy until tdayear 229 , was composed more than one hunnit yrs after Nerva done died . Further details are added by an abridged biography from the Epitome de Caesaribus , a wrk alleged to done been authored by the 4th @-@ century historian Aurelius Victor .