Ancient kingdom, central England.
One of the Anglo-Saxon kingdoms of the Heptarchy, it comprised the border areas, corresponding to modern Staffordshire , Derbyshire , Nottinghamshire , and northern West Midlands and Warwickshire . Offa , who ruled from 757 to 796, created a single state from the River Humber to the English Channel. After Offa's death, Mercia declined, overshadowed by Wessex . In 877 the Danes divided Mercia into English and Danish sections. After the reconquest of the Danish lands in the early 10th century, it came under the rule of Wessex.