Mercia was one of the kingdoms of the Anglo-Saxon Heptarchy. It was centered on the valley of the River Trent and its tributaries in the region now known as the English Midlands. The name is a Latinisation of the Old English Mierce or Myrce, meaning "border people".
Mercia's neighbours included Northumbria, Powys and the kingdoms of southern Wales, Wessex, Sussex, Essex and East Anglia.
The name Mercia is still in use today by a wide range of organisations, including military units, public, commercial and voluntary bodies; and occurs as a female given name.