Görlitz in Lausitz. The citizens of the five Thuringian Färberwaid (dye woad) towns of Erfurt, Gotha, Tennstedt, Arnstadt and Langensalza had their own charters. In Erfurt, the woad-traders gave the funds to found the University of Erfurt. Traditional fabric is still printed with woad in Thuringia, Saxony and Lusatia today: it is known as Blaudruck (literally, "blue print(ing)"). Use as Chinese medicine The woad plant's roots are used in Traditional Chinese medicine to make a medicine known as banlangen ( ) that purports to have antiviral properties. Banlangen is used as an herbal medicinal tea in China for colds and tonsular ailments. Used as a tea, it has a brownish appearance and (unlike most Chinese medicines) is mildly sweet in taste. Woad and indigo The dye chemical extracted from woad is indigo, the same dye extracted from "true indigo", Indigofera tinctoria, but in a lower concentration. Following the Portuguese discovery of the sea route to India by the navigator Vasco da Gama in 1498, great amounts of indigo were imported from Asia. Laws were passed in some parts of Europe to protect the woad industry from the competition of the indigo trade. It was proclaimed that indigo caused yarns to rot: "In 1577 the German government officially prohibited the use of indigo, denouncing it as that pernicious, deceitful and corrosive substance, the Devil's dye." This prohibition was repeated in 1594 and again in 1603. In France, Henry IV, in an edict of 1609, forbade under pain of death the use of "the false and pernicious Indian drug". With the development of a chemical process to synthesize the pigment, both the woad and natural indigo industries collapsed in the first years of the 20th century. The last commercial harvest of woad until recent times occurred in 1932, in Lincolnshire, Britain. Small amounts of woad are now grown in the UK and France to supply craft dyers. The classic book about woad is The Woad Plant and its Dye by J. B. Hurry, Oxford University Press of 1930, which contains an extensive bibliography. A method for producing blue dye from woad is described in The History of Woad and the Medieval Woad Vat (1998) . In France, woad was treated with human urine, by a profession known as pisseurs, who would drink large quantities of beer to provide a sufficient supply. Woad is biodegradable and safe in the environment. In Germany, there