Glass blowing was invented in the Syro-Palestinian region during the Parthian period in the mid-first century B.C.E. and quickly spread from there to neighboring regions. Production of glass was much more widely spread within the Sasanian empire; it also became in both shapes and types of decoration independent from Parthian prototypes.
Bullae, the sealings, usually of clay or bitumen, on which were impressed the marks of seals showing ownership or witness to whatever was attached to the sealing. Bullae or clay sealings were used in ancient Mesopotamia, but strictly speaking bullae came into general use after the end of cuneiform writing. The earliest bullae date from the Seleucid period of the history of Iran and they were in the shape of a “napkin ring” around a document. Seals were then impressed on the clay ring, usually with strings imbedded in it. This method of “sealing” documents apparently did not continue later, for under the Parthians we find a piece of clay placed over a knot that tied a folded parchment or papyrus as at Avroman.