Mercia
Penda (–655) was a pagan king of Mercia. He was able to put together a confederacy of a number of smaller kingdoms and from that he created Mercia. But in the 630s he was not able to compete with the larger Anglo-Saxon kingdoms that were around his. Northumberland was threatening to expand into the territory of Mercia. Penda found it convenient to ally with Gwynedd, the dominant British kingdom to the west. It was an unusual cooperation between Christians and pagans, but it worked. Together they defeated the Northumbrian king, Edwin, who died at the battle of Hatfield Chase.