History of glass
Glass remained a luxury material, and the disasters that overtook Late Bronze Age civilizations seem to have brought glass-making to a halt. It picked up again in its former sites, Syria and Cyprus, in the 9th century BC, when the techniques for making colorless glass were discovered. The first glassmaking "manual" dates back to ca. 650 BC. Instructions on how to make glass are contained in cuneiform tablets discovered in the library of the Assyrian king Ashurbanipal. In Egypt glass-making did not revive until it was reintroduced in Ptolemaic Alexandria. Core-formed vessels and beads were still widely produced, but other techniques came to the fore with experimentation and technological advancements. During the Hellenistic period many new techniques of glass production were introduced and glass began to be used to make larger pieces, notably table wares. Techniques developed during this period include 'slumping' viscous (but not fully molten) glass over a mould in order to form a dish and 'millefiori' (meaning 'thousand flowers') technique, where canes of multicolored glass were sliced and the slices arranged together and fused in a mould to create a mosaic-like effect. It was also during this period that colorless or decolored glass began to be prized and methods for achieving this effect were investigated more fully.
Ancient glass trade
Glass shows up in Northern India at the end of the 2nd millennium BC becoming more common throughout South East Asia during the following millennium. Glass beads in particular become extremely popular and together with bangles form the largest group of glass finds. From its Indian origins, glass beads spread to an area from Africa to Japan, sailing with the monsoon winds and leading to their christening as 'Trade wind beads'. The most common compositional type, representing 40% of the glass finds for the region, is known as mineral soda-alumina glass and is found from the 4th century BC to the 16th century AD. As the name indicates this it is typically characterized by a high alumina content and was made by the probably melting of "reh" with local, alumina rich, sands. Through LA-ICP-MS analysis, however, Carter found that Cambodia had a large amount of glass beads made of potash glass and predominantly high alumina soda glass. Potash glass is a glass that uses potash or K2O as a flux in order to decrease the melting point of the glass and is the most common type of glass found in SE Asia.