Iron Age remnants have not been detected until the Late Iron Age, with various local chieftain burials dated to the 1st Century BC gaining national prominence. The Belgae Celtic culture colonised much of South-Eastern England in the 1st century BC, with Welwyn in the area believed to have been settled by the Catuvellauni tribe. In Graham Robb's book "The Ancient Paths" there is a suggestion that Welwyn lay on a late-Celtic highway running in the direction of the summer solstice angle straight from Bury St Edmunds to Salisbury via the Catuvellauni headquarters at Verlamion outside modern-day St Albans. Separately, it can be shown that the line of the Roman road through Welwyn (see below) is in a direct alignment with the pre-Roman Belgic tribal centres of Verlamion (for the Catuvellauni) and Venta Icenorum for the Iceni tribe.