▁earlier . ▁ ▁Bon nie ▁J . ▁Black burn ▁and ▁Le of ran c ▁Hol ford - St re vens ▁briefly ▁present ▁arguments ▁for ▁ 2 ▁BC , ▁ 1 ▁BC , ▁or ▁AD ▁ 1 ▁as ▁the ▁year ▁D ion ys ius ▁intended ▁for ▁the ▁N ativity ▁or ▁inc arn ation . ▁Among ▁the ▁sources ▁of ▁confusion ▁are : ▁ ▁In ▁modern ▁times , ▁inc arn ation ▁is ▁syn onymous ▁with ▁the ▁conception , ▁but ▁some ▁ancient ▁writers , ▁such ▁as ▁B ede , ▁considered ▁inc arn ation ▁to ▁be ▁syn onymous ▁with ▁the ▁N ativity . ▁ ▁The ▁civil ▁or ▁cons ular ▁year ▁began ▁on ▁ 1 ▁January ▁but ▁the ▁Dioc let ian ▁year ▁began ▁on ▁ 2 9 ▁August ▁( 3 0 ▁August ▁in ▁the ▁year ▁before ▁a ▁Julian ▁le ap ▁year ). ▁ ▁There ▁were ▁in acc ura cies ▁in ▁the ▁lists ▁of ▁cons uls . ▁ ▁There ▁were ▁confused ▁summ ations ▁of ▁em per ors ' ▁reg nal ▁years . ▁ ▁It ▁is ▁not ▁known ▁how ▁D ion ys ius ▁established ▁the ▁year ▁of ▁Jesus ' s ▁birth . ▁Two ▁major ▁theories ▁are ▁that ▁D ion ys ius ▁based ▁his ▁calculation ▁on ▁the ▁G ospel ▁of ▁Luke , ▁which ▁states ▁that ▁Jesus ▁was ▁" about ▁thirty ▁years ▁old " ▁shortly ▁after ▁" the ▁fif teenth ▁year ▁of ▁the ▁reign ▁of ▁T iber ius ▁Ca esar ", ▁and ▁hence ▁subtract ed ▁thirty ▁years ▁from ▁that ▁date , ▁or ▁that ▁D ion ys ius ▁counted ▁back ▁ 5 3 2