The ranking shows up to 25 rulers of the succession cluster ordered by the maximal extension the succession cluster had during their rule. Individual battles and fronts are excluded.

Rulers are considered only when they can be clearly defined. Phersu Atlas includes de facto rulers, which may sometimes be subjective. As a result, the ruler could be a King, President, or others depending on the context.

Cluster is a categorization that includes all iterations of a nation and all the possessions of this nation. Example: the cluster spain includes the iterations of that nation, like the Kingdom of Spain and the First Spanish Republic, whereas possessions of spain include Spanish America and the Spanish Philippines. Succession clusters do only include all the iteration of a nation without its possessions (colonies, protectorates, etc).