The name is Celto-British in derivation, and may be named after the Iceni tribe. They may have established this route to permit trade with other parts of the country from their base in East Anglia. It has also been suggested that the road has older prehistoric origins. The name is also said to have been initially used for the part to the west and south (i.e. south of the River Thames) but now refers usually to the track or traces north of the Thames.