In common with other urbanized and state-organized societies, the Etruscans developed strategies for organizing time. The maximum life of individuals was organized in terms of twelve sevenyear tranches. The life of the city and the state were organized in ten saecula of variable length that was possible to predict by the time the Etruscan cities had been conquered by the Romans. The expedient calculation of the length of individual saecula was in the hands of the augurs. Late sources calculate that the first four saecula were 100 years long, the fifth was 123, and the sixth and seventh were 119.
Historical Dictionary of the Etruscans. Simon K. F. Stoddart.