The language spoken during this period is thought to be Southwestern Brythonic, but only one or two inscribed stones survive in Somerset from this period. However, a couple of curse tablets found in the baths at Bath may be in this language. Some place names in Somerset seem to be Celtic in origin and may be from this period or earlier, e.g. Tarnock. Some river names, such as Parrett, may be Celtic or pre-Celtic. The religion of the people of Somerset in this period is thought to be Christian but it was isolated from Rome until after the Council of Hertford in 673 AD when Aldhelm was asked to write a letter to Geraint of Dumnonia and his bishops. Some church sites in Somerset are thought to date from this period, e.g., Llantokay Street.