The early Middle Ages glass.

Archaeological excavations on the island of Torcello near Venice, Italy, have unearthed objects from the late 7th and early 8th centuries which bear witness to the transition from ancient to early Middle Ages production of glass.

Towards the year 1000, a significant change in European glassmaking techniques took place. Given the difficulties in importing raw materials, soda glass was gradually replaced by glass made using the potash obtained from the burning of trees. At this point, glass made north of the Alps began to differ from glass made in the Mediterranean area, with Italy, for example, sticking to soda ash as its dominant raw material.