The prosperity of Brig is bound up with the Simplon Pass, so that it gradually supplanted the more ancient village of Naters opposite, becoming a separate parish (the church is at Glis, a few minutes from the town) in 1517. Its medieval name was Briga dives. The opening of the carriage road across the Simplon (1807) and of the tunnel beneath the pass (1906), as well as the fact that above Brig is the steeper and less fertile portion of the Upper Valais (then much frequented by tourists), greatly increased the importance and size of the town.