Dorchester on Thames (or Dorchester-on-Thames) is a village and civil parish in Oxfordshire, about northwest of Wallingford and southeast of Oxford. The town is a few hundred yards from the confluence of the River Thames and River Thame. A common practice of the scholars at Oxford was to refer to the river Thames by two separate names, with Dorchester on Thames the point of change. Downstream of the village, the river continued to be named The Thames, while upstream it was named The Isis. Ordnance Survey maps continued the practice by labelling the river as "River Thames or Isis" above Dorchester, however, this distinction is rarely made outside the city of Oxford. Etymology The town shares its name with Dorchester in Dorset, but there has been no proven link between the two names. The name is likely a combination of a Celtic or Pre-Celtic element "-Dor" with the common suffixation "Chester" (Old English: "A Roman town or Fort"). As Dorchester on Thames is surrounded on three sides by water (and may have been founded at the point where the river became navigable), it is likely the name is linked to the Celtic word for water "dwfr" (or "dŵr" as in modern Modern Welsh), giving a meaning of "Fort on the Water" or "Water-town". This etymology was known as early as 1545 when it was used by John Leland in his epic poem Cygnea Cantio ("Song of the Swan"). In the poem Leland refers to the town with a Greek translation, Hydropolis ( "Water-city"). There is no surviving record of the settlement's Latin name, and Bede's reference to the town as "Dorcic" is otherwise unsupported. History The area has been inhabited since at least the Neolithic. In the north of the parish there was a Neolithic sacred site, now largely destroyed by gravel pits. On one of the Sinodun Hills on the opposite side of the Thames, a ramparted settlement was inhabited during the Bronze Age and Iron Age. Two of the Sinodun Hills bear distinctive landmarks of mature trees called Wittenham Clumps. Adjacent to the village is Dyke Hills which is the remains of an Iron Age hill fort. The Romans built a vicus here, with a road linking the settlement to a military camp at Alchester, 16 miles (25 km) to the north. In 634 Pope Honorius I sent a bishop called Birinus to convert the Saxons of the