Neolithic period (5,3)
I believe the answer is:
stone age
'neolithic period' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for stone age that I've seen before include "Old time" , "Primitive period" , "Earliest known period of human culture" , "Go, senate to ancient era before metal was discovered" , "time long ago" .)