Regarding chemistry and metallurgy too, some progress was made in ancient times. The Harappans developed metallurgy of copper and bronze about 2500 B.C. The Vedic Aryans tanned leather, fermented grains and fruits, and dyed scale production of copper, iron and steel, brass, silver and gold and their alloys. Indian steel was highly esteemed in the ancient world and it was exported in large quantities.