When would a historian use a timeline

For example, a broad timeline of human history might include the Ancient Age (from 3600 B. C. to roughly 500 A. D), the Middle Ages (500 to 1500), and the Modern Age (1500 to the present). Timelines show us the chronology of historical eras. Chronology is simply the order in which events take place, from first to last.

a lot

Explanation:

a historian would use a timeline when seeing and or seting up a chronological order in witch events in history happened such as WW1 and WW2 to see when in WW1 Hitler was not in charge and then going through to WW2 him taking charge and commanding the Nazis