1911 Encyclopædia Britannica/Heptarchy
HEPTARCHY (Gr. ἑπτά, seven, and ἀρχή, rule), a word which is frequently used to designate the period of English history between the coming of the Anglo-Saxons in 449 and the union of the kingdoms under Ecgbert in 828. It was first used during the 16th century because of the belief held by Camden and other older historians, that during this period there were exactly seven kingdoms in England, these being Northumbria, Mercia, East Anglia, Essex, Kent, Sussex and Wessex. This belief is erroneous, as the number of kingdoms varied considerably from time to time; nevertheless the word still serves a useful purpose to denote the period.