The idea of a heptarchy, a group of seven independent kingdoms, is thought to have come from the English historian Henry of Huntingdon in the 12th century. He listed the seven Anglo-Saxon kingdoms in his "Historia Anglorum" (History of the English People). Bede, however, set up the idea that several kingdoms were more dominant than others (at different times). He created a list of kings who dominated the other kingdoms. The dividing line between these kingdoms was the River Humber. Northumbria (Deira and Bernicia) was the northern kingdom while the remaining kingdoms were those of the southern English. The actual term 'heptarchy' was first used in the 16th century by William Lambarde. His 1568 woodcut map is the earliest known use of the term.