polished plate glass is produced for the first time (around 2100 B.C.)
One of the main ingredients for glass is silicia. This was readily available on sites in the Ancient Near East since it is the main constituent of desert sand. There is a distinciton between glass-making from its raw materials and glass-working from raw glass. The first is considerable more difficult than the second. Glass-making remained precarious well beyond the middle ot the nineteenth century AD!