What does "heptarchy" mean?

Heptarchy: A government by seven persons; also, a country under seven rulers. Note: The word is most commonly applied to England, when it was divided into seven kingdoms; as, the Saxon heptachy, which consisted of Kent, the South Saxons (Sussex), West Saxons (Wessex), East Saxons (Essex), the East Angles, Mercia, and Northumberland.