The Ancalites were a Celtic tribe, probably living around the Thames Valley

Thames Valley

The Thames Valley Region is a loose term for the English counties and towns roughly following the course of the River Thames as it flows from Oxfordshire in the west to London in the east. It includes parts of Buckinghamshire, Berkshire, North Hampshire, Surrey and west London...

 area in the 1st century BC. They are known only from the writings of Julius Caesar

Julius Caesar

Gaius Julius Caesar was a Roman general and statesman and a distinguished writer of Latin prose. He played a critical role in the gradual transformation of the Roman Republic into the Roman Empire....

.

Caesar made his second invasion of Britain

Caesar's invasions of Britain

In his Gallic Wars, Julius Caesar invaded Britain twice, in 55 and 54 BC. The first invasion, made late in summer, was either intended as a full invasion or a reconnaissance-in-force expedition...

 in 54 BC, and achieved some measure of success, advancing as far as modern day Greater London

Greater London

Greater London is the top-level administrative division of England covering London. It was created in 1965 and spans the City of London, including Middle Temple and Inner Temple, and the 32 London boroughs. This territory is coterminate with the London Government Office Region and the London...

, and restoring a friendly king, Mandubracius

Mandubracius

Mandubracius or Mandubratius was a king of the Trinovantes of south-eastern Britain in the 1st century BC.-History:Mandubracius was the son of a Trinovantian king, named Imanuentius in some manuscripts of Julius Caesar's De Bello Gallico, who was overthrown and killed by the warlord Cassivellaunus...

 of the Trinovantes

Trinovantes

The Trinovantes or Trinobantes were one of the tribes of pre-Roman Britain. Their territory was on the north side of the Thames estuary in current Essex and Suffolk, and included lands now located in Greater London. They were bordered to the north by the Iceni, and to the west by the Catuvellauni...

, whose father had been deposed by his rival Cassivellaunus

Cassivellaunus

Cassivellaunus was an historical British chieftain who led the defence against Julius Caesar's second expedition to Britain in 54 BC. The first British person whose name is recorded, Cassivellaunus led an alliance of tribes against Roman forces, but eventually surrendered after his location was...

. Cassivellaunus led the British opposition to Caesar's incursion, but this led to divided loyalties among the Britons, as Caesar records. Emissaries of five British tribes, including the Ancalites (the others being the Cenimagni

Cenimagni

The Cenimagni was a Celtic tribe, probably living somewhere in Southern England in the 1st century BC. They are known only from the writings of Julius Caesar...

, the Segontiaci

Segontiaci

The Segontiaci were a tribe of Iron Age Britain encountered by Julius Caesar during his second expedition to Britain in 55 BC. They surrendered to him as he was campaigning against Cassivellaunus in the Thames Valley, which suggests they were also based in the south-east...

, the Bibroci

Bibroci

The Bibroci were a tribe of Iron Age Britain encountered by Julius Caesar during his second expedition to Britain in 55 BC. They surrendered to him as he was campaigning against Cassivellaunus in the Thames Valley, which suggests they were also based in the south-east....

 and the Cassi

Cassi

The Cassi are one of five tribes encountered by Julius Caesar during his second expedition to Britain in 55 BC when he crossed the Thames at Kew, and who became his allies after the Trinovantes joined him...

), arrived at the Roman camp to treat for peace, and revealed to him the location of Cassivellaunus' stronghold. Caesar besieged him there and brought him to terms. When Caesar left Britain he took hostage

Hostage

A hostage is a person or entity which is held by a captor. The original definition meant that this was handed over by one of two belligerent parties to the other or seized as security for the carrying out of an agreement, or as a preventive measure against certain acts of war...

s of the Britons, although whether the Ancalites were compelled to give any is not specified.

Where exactly the Ancalites were based is not known. In the 16th century William Camden

William Camden

William Camden was an English antiquarian, historian, topographer, and officer of arms. He wrote the first chorographical survey of the islands of Great Britain and Ireland and the first detailed historical account of the reign of Elizabeth I of England.- Early years :Camden was born in London...

 reported that "some doe thinke" the Ancalites inhabited the area around Henley

Henley-on-Thames

Henley-on-Thames is a town and civil parish on the River Thames in South Oxfordshire, England, about 10 miles downstream and north-east from Reading, 10 miles upstream and west from Maidenhead...

, Oxfordshire

Oxfordshire

Oxfordshire is a county in the South East region of England, bordering on Warwickshire and Northamptonshire , Buckinghamshire , Berkshire , Wiltshire and Gloucestershire ....

, and the Wiltshire

Wiltshire

Wiltshire is a ceremonial county in South West England. It is landlocked and borders the counties of Dorset, Somerset, Hampshire, Gloucestershire, Oxfordshire and Berkshire. It contains the unitary authority of Swindon and covers...

 tourist board claim them amongst Wiltshire's own ethnic ancestry, which would significantly increase their territory, but without archaeological

Archaeology

Archaeology, or archeology , is the study of human society, primarily through the recovery and analysis of the material culture and environmental data that they have left behind, which includes artifacts, architecture, biofacts and cultural landscapes...

evidence, none of this can be confirmed.