Many English places derive part of their name from the river upon which they were built, but in the 16th century many English rivers were renamed with back-formations from towns on their banks. Cambridge, perhaps uniquely, illustrates both effects: originally "Grontabricc", a bridge on the Granta, the name became "Cantebruge" and then "Cambrugge", from which the river was renamed Cam. The scholars of Oxford renamed the upper course of the River Thames running through Oxford to Dorchester-on-Thames as the "Isis", owing to an incorrect assumption that the Latin name of the river, Tamesis, represented a combination of "Thame" (a river that joins the Thames at Dorchester) and "Isis".