<P> Between the 1st and 3rd centuries , the Roman Empire gradually replaced the eight - day Roman nundinal cycle with the seven - day week . Our earliest evidence for this new system is a Pompeiian graffito referring to the 6th February ( viii idus Februarius ) of the year AD 60 as dies solis ( `` Sunday '' ) . Another early witness is a reference to a lost treatise by Plutarch , written in about AD 100 , which addressed the question of Why are the days named after the planets reckoned in a different order from the actual order ? . </P>
<P> Between the 1st and 3rd centuries , the Roman Empire gradually replaced the eight - day Roman nundinal cycle with the seven - day week . Our earliest evidence for this new system is a Pompeiian graffito referring to the 6th February ( viii idus Februarius ) of the year AD 60 as dies solis ( `` Sunday '' ) . Another early witness is a reference to a lost treatise by Plutarch , written in about AD 100 , which addressed the question of Why are the days named after the planets reckoned in a different order from the actual order ? . </P>
when did they start naming the days of the week
when did they start naming the days of the week
Between the 1st and 3rd centuries
Between the 1st and 3rd centuries