Focus for a historian (3)
I believe the answer is:
era
(Other definitions for era that I've seen before include "Are involved in time span" , "Aeon" , "Age of importance" , "Distinctive period of time" , "Long stretch" .)
I believe the answer is:
era
(Other definitions for era that I've seen before include "Are involved in time span" , "Aeon" , "Age of importance" , "Distinctive period of time" , "Long stretch" .)