"This is about the historiographical convention. See History of Anglo-Saxon England for a historical discussion, and List of Anglo-Saxon kingdoms for a full list.The Heptarchy (from the Greek \u1F11\u03C0\u03C4\u03AC hepta, \"seven\" and \u1F04\u03C1\u03C7\u03C9 arkho, \"to rule\") is a collective name applied to the Anglo-Saxon kingdoms of south, east, and central England during late antiquity and the early Middle Ages, conventionally identified as seven: East Anglia, Essex, Kent, Mercia, Northumbria, Sussex, and Wessex."@en . . .