In Trommsdorfstraße, Erfurt, a glass-processing workshop has been excavated, which produced lead glass rings and beads in the 13th century. This workshop produced two different lead glasses. The first, a high-lead glass, could be found throughout Europe, from England to Russia. However, another newly defined type of glass could be identified (Central European lead–ash glass). This can be demonstrated by analysing the literature, and it has been found in eastern Germany, Poland, Slovakia and the Czech Republic. A Slavic lead–ash glass with the same ash content as the Central European lead–ash glass but lower amounts of lead was produced in Eastern Europe. In western Germany, another type of ash (beech ash) was used to produce a wood-ash lead glass. Lead-isotope analysis proved that the same source of lead was used for the wood-ash lead glass and the high-lead glass in western Germany and the two types of glass from Erfurt.