Oxfordshire was recorded as a county in the early years of the 10th century and lies between the River Thames to the south, the Cotswolds to the west, the Chilterns to the east and the Midlands to the north, with spurs running south to Henley-on-Thames and north to Banbury.
Although it had some significance as an area of valuable agricultural land in the centre of the country, it was largely ignored by the Romans, and did not grow in importance until the formation of a settlement at Oxford in the 8th century. Alfred the Great was born across the Thames in Wantage, Vale of White Horse. The University of Oxford was founded in 1096, though its collegiate structure did not develop until later on. The university in the county town of Oxford (whose name came from Anglo-Saxon Oxenaford = "ford for oxen") grew in importance during the Middle Ages and early modern period. The area was part of the Cotswolds wool trade from the 13th century, generating much wealth, particularly in the western portions of the county in the Oxfordshire Cotswolds. Morris Motors was founded in Oxford in 1912, bringing heavy industry to an otherwise agricultural county. The importance of agriculture as an employer has declined rapidly in the 20th century though; currently under one percent of the county's population are involved due to high mechanisation. Nonetheless, Oxfordshire remains a very agricultural county by land use, with a lower population than neighbouring Berkshire and Buckinghamshire, which are both smaller.
Throughout most of its history the county was divided into fourteen hundreds, namely Bampton, Banbury, Binfield, Bloxham, Bullingdon, Chadlington, Dorchester, Ewelme, Langtree, Lewknor, Pyrton, Ploughley, Thame and Wootton.
The Oxfordshire and Buckinghamshire Light Infantry, the main army unit in the area, was based at Cowley Barracks on Bullingdon Green, Cowley.
The Vale of White Horse district and parts of the South Oxfordshire administrative district south of the River Thames were historically part of Berkshire, but in 1974 Abingdon, Didcot, Faringdon, Wallingford and Wantage were added to the administrative county of Oxfordshire under the Local Government Act 1972. Conversely, the Caversham area of Reading, now administratively in Berkshire, was historically part of Oxfordshire as was the parish of Stokenchurch, now administratively in Buckinghamshire.