After the Romans abandoned Britain, little or nothing is known about metallurgy during Saxon times; but in the days of the Plantagenet kings, Britain was certainly being supplied from the Continent with its copper, mainly from Germany. During the 13th Century the valuable and very extensive copper ore at Mansfeld was being exploited and there was an equally famous mine in operation at Falun, Sweden, about 1oo miles north-west of Stockholm. Not until Tudor days did English copper mining again get under way, when digging began in Cumberland and subsequently in Cornwall; German miners were imported specially for the purpose. These local developments led to the establishment of the Mines Royal at Swansea (page 44). The industry, which also involved the production of brass from calamine found in the Mendip Hills, became centred in this region; and Swansea continued to be the chief centre for smelting and refining copper from all over the world until the mid-Victorian period.