 This unit of Varduli had its origins in Hispania Tarraconensis, Gipuzkoa, in northern Spain, where the unit was raised.This unit was also present at other forts in the Britannia Superior, such as Castlecary, Bremenium (High Rochester), Corstopitum (Corbridge) and milecastle 19 on Hadrian's Wall.The Tarraconensis region of Spain was the most important source of gold, tin, copper and other metals and minerals in the entire Roman Empire, and the Romans applied water power on a large scale for hydraulic mining using aqueducts to tap the local rivers.