Mercia
was one of the kingdoms of the Anglo-Saxon

Anglo-Saxons

Anglo-Saxon is a term used by historians to designate the Germanic tribes who invaded and settled the south and east of Great Britain beginning in the early 5th century AD, and the period from their creation of the English nation to the Norman conquest. The Anglo-Saxon Era denotes the period of...

 Heptarchy

Heptarchy

The Heptarchy is a collective name applied to the Anglo-Saxon kingdoms of south, east, and central Great Britain during late antiquity and the early Middle Ages, conventionally identified as seven: Northumbria, Mercia, East Anglia, Essex, Kent, Sussex and Wessex...

. It was centred on the valley of the River Trent

River Trent

The River Trent is one of the major rivers of England. Its source is in Staffordshire on the southern edge of Biddulph Moor. It flows through the Midlands until it joins the River Ouse at Trent Falls to form the Humber Estuary, which empties into the North Sea below Hull and Immingham.The Trent...

 and its tributaries in the region now known as the English Midlands

English Midlands

The Midlands, or the English Midlands, is the traditional name for the area comprising central England that broadly corresponds to the early medieval Kingdom of Mercia. It borders Southern England, Northern England, East Anglia and Wales. Its largest city is Birmingham, and it was an important...

. The name is a Latinisation

Latinisation (literature)

Latinisation is the practice of rendering a non-Latin name in a Latin style. It is commonly met with for historical personal names, with toponyms, or for the standard binomial nomenclature of the life sciences. It goes further than Romanisation, which is the writing of a word in the Latin alphabet...

 of the Old English Mierce or Myrce, meaning "border people".

Mercia's neighbours included Northumbria

Northumbria

Northumbria was a medieval kingdom of the Angles, in what is now Northern England and South-East Scotland, becoming subsequently an earldom in a united Anglo-Saxon kingdom of England. The name reflects the approximate southern limit to the kingdom's territory, the Humber Estuary.Northumbria was...

, Powys, the kingdoms of southern Wales

Wales

Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

, Wessex

Wessex

The Kingdom of Wessex or Kingdom of the West Saxons was an Anglo-Saxon kingdom of the West Saxons, in South West England, from the 6th century, until the emergence of a united English state in the 10th century, under the Wessex dynasty. It was to be an earldom after Canute the Great's conquest...

, Sussex

Kingdom of Sussex

The Kingdom of Sussex or Kingdom of the South Saxons was a Saxon colony and later independent kingdom of the Saxons, on the south coast of England. Its boundaries coincided in general with those of the earlier kingdom of the Regnenses and the later county of Sussex. A large part of its territory...

, Essex

Kingdom of Essex

The Kingdom of Essex or Kingdom of the East Saxons was one of the seven traditional kingdoms of the so-called Anglo-Saxon Heptarchy. It was founded in the 6th century and covered the territory later occupied by the counties of Essex, Hertfordshire, Middlesex and Kent. Kings of Essex were...

, and East Anglia

Kingdom of the East Angles

The Kingdom of East Anglia, also known as the Kingdom of the East Angles , was a small independent Anglo-Saxon kingdom that comprised what are now the English counties of Norfolk and Suffolk and perhaps the eastern part of the Fens...

.

The name Mercia is still in use today by a wide range of organisations, including military units, public, commercial and voluntary bodies.
Mercia's exact evolution from the Anglo-Saxon

Anglo-Saxons

Anglo-Saxon is a term used by historians to designate the Germanic tribes who invaded and settled the south and east of Great Britain beginning in the early 5th century AD, and the period from their creation of the English nation to the Norman conquest. The Anglo-Saxon Era denotes the period of...

 invasions is more obscure than that of Northumbria

Northumbria

Northumbria was a medieval kingdom of the Angles, in what is now Northern England and South-East Scotland, becoming subsequently an earldom in a united Anglo-Saxon kingdom of England. The name reflects the approximate southern limit to the kingdom's territory, the Humber Estuary.Northumbria was...

, Kent

History of Kent

Kent is a county in South East England with a long history of human occupation.-Prehistoric Kent:Kent has been occupied since the Lower Palaeolithic as finds from the quarries at Swanscombe attest...

, or even Wessex

Wessex

The Kingdom of Wessex or Kingdom of the West Saxons was an Anglo-Saxon kingdom of the West Saxons, in South West England, from the 6th century, until the emergence of a united English state in the 10th century, under the Wessex dynasty. It was to be an earldom after Canute the Great's conquest...

.