No detailed study has ever been made of the East Saxon kingdom, and general works of Anglo-Saxon history usually devote only a few lines to it. Some incidents are well known, such as the conversion of Saberht in 604 by his uncle Æthelberht of Kent, and the apostacy of Sigehere during the plague of 664, while his co-ruler Sæbbi remained Christian. These events are frequently cited as evidence for the workings of overlordship or for the existence of joint kingship in Anglo-Saxon England, though in order to appreciate their true significance they must be placed in a wider context of East Saxon history. Other events from the East Saxon past are less well known, but the fact that East Saxon kings ruled part of Kent for at least six years and that their royal family was one of the few to survive until the ninth century are indications that the East Saxon province was one of the more significant minor kingdoms. Their relative neglect is due to the scarcity of written sources: no East Saxon chronicle has survived, and charters are few and often imperfectly recorded. Inevitably many areas of the East Saxon past must remain obscure, but the situation is not as bleak as it might first appear. East Saxon sources, although few, are varied, and illuminate different aspects of the kingdom's history. The evidence they contain is reviewed first, before more general conclusions are drawn about the East Saxon system of kingship and the relations of East Saxon kings with other kingdoms.