Naturally occurring glass, such as volcanic obsidian glass, have been known since the Stone Age. Manufactured glass, glass blowing, and glass art is much more recent. History suggests that manufactured glass began as early as 3,500 BC as a by-product of metalworking. Archaeological evidence indicates that the earliest glass manufacturers were found in what is now Syria, Egypt, Turkey, and Iran. Techniques were developed to make carvings, beads, vessels, building materials, and other glass products. Glass making spread throughout Western Asia (aka the “Middle East”) and later to Europe (especially Italy) and then across Asia to India and China.