"Northumbria." YourDictionary, n.d. Web. 20 October 2018. <http://www.yourdictionary.com/northumbria>.
Northumbria. (n.d.). Retrieved October 20th, 2018, from http://www.yourdictionary.com/northumbria
An Anglian kingdom of northern England formed in the seventh century by the union of Bernicia and Deira. Much of Northumbria fell to invading Danes in the ninth century and was annexed to Wessex in 954.
Both these kings were slain by .Ceadwalla in the following year, but shortly afterwards the Welsh king was overthrown by Oswald, brother of Eanfrith, who reunited the whole of Northumbria under his sway and acquired a supremacy analogous to that previously held by Edwin.
He was succeeded in 705 by his son Osred, and under him and his successors Northumbria began rapidly to decline through the vices of its kings and the extravagance of their donations.
It was during his reign in 827 that Northumbria acknowledged the supremacy of Ecgberht, king of Wessex.
The southern part of Northumbria now passed entirely into the hands of the invaders, but they allowed a certain Ecgberht to reign over the portion of the kingdom north of the Tyne.
In the winter of 874-875 Healfdene returned to Northumbria, which he partitioned among his followers.