Periodization is a useful concept to apply when organizing Roman history into 3 main eras.
In terms of history, periodization is understood as the process of studying, analyzing and categorizing events of the past into quantified and named block of time. Periodization is intended to make the analysis of historical events easier as well as understanding the reasons of specific historical processes.
The process results in descriptive abstractions that provide convenient terms for periods of time with stable characteristics.