History of glass
The history of glass-making dates back to at least 3600 years ago in Mesopotamia. However, they may have been producing second-rate copies of glass objects from Egypt, where this complex craft originated. Other archaeological evidence suggests that the first true glass was made in coastal north Syria, Mesopotamia or Egypt. The earliest known glass objects, of the mid second millennium BC, were beads, perhaps initially created as the accidental by-products of metal-working (slags) or during the production of faience, a pre-glass vitreous material made by a process similar to glazing. Glass products remained a luxury until the disasters that overtook the late Bronze Age civilizations seemingly brought glass-making to a halt.
Lead glass
Glasses with lead oxide content first appeared in Mesopotamia, the birthplace of the glass industry. The earliest known example is a blue glass fragment from Nippur dated to 1400 BC containing 3.66% PbO. Glass is mentioned in clay tablets from the reign of Assurbanipal (668–631 BC), and a recipe for lead glaze appears in a Babylonian tablet of 1700 BC. A red sealing-wax cake found in the Burnt Palace at Nimrud, from the early 6th century BC, contains 10% PbO. These low values suggest that lead oxide may not have been consciously added, and was certainly not used as the primary fluxing agent in ancient glasses.