Some regnal lists may give the relationship between successive monarchs (e.g., son, brother), the length of reign of each monarch or annotations on important reigns.
As a distinct genre, the regnal list originates in the ancient Near East.
It originally served to demonstrate the antiquity and legitimacy of the monarchy, but it became an important device for structuring historical narratives (as in Herodotus) and thus a chronological aid.
[1] In antiquity, regnal lists were kept in Sumer, Egypt, Israel, Assyria and Babylonia.
[2] Regnal lists were kept in early medieval Ireland, Pictland and Anglo-Saxon England.