The History of metallurgy in the Indian subcontinent dates back to 1700 BCE. Metals and related concepts were mentioned in various early Vedic age texts. The Rigveda already uses the Sanskrit term Ayas (metal).
The Atharva Veda and the Satapatha Brahmana refer to krsna ayas ("black metal"), which could be iron (but possibly also iron ore and iron items not made of smelted iron).
In the Taittiriya Samhita are references to ayas and at least one reference to smiths.
The Satapatha Brahmana 18.104.22.168 refers to the smelting of metallic ore.
In the Manu Smriti (6.71), the following analogy is found: "For as the impurities of metallic ores, melted in the blast (of a furnace), are consumed, even so the taints of the organs are destroyed through the suppression of the breath."
The Rasa Ratnasamuccaya describes the extraction and use of copper.
The pillar of Delhi, erected by Chandragupta II Vikramaditya (375-413), made up of 98% wrought iron of pure quality is a testament to the high level of skill achieved by ancient Indian iron smiths in the extraction and processing of iron. It has attracted the attention of archaeologists and metallurgists as it has withstood corrosion for the last 1600 years, despite harsh weather.
Metallurgists at IIT Kanpur have claimed that a thin layer of "misawite", a compound (amorphous phase d-FeOOH) of iron, oxygen, and hydrogen, has protected the wrought iron pillar from rust.