The history of metallurgy in the Indian subcontinent began prior to the 3rd millennium BCE.See Tewari (2003) and Arnold, 100-101. Metals and related concepts were mentioned in various early Vedic age texts. The Rigveda already uses the Sanskrit term ayas (). The Indian cultural and commercial contacts with the Near East and the Greco-Roman world enabled an exchange of metallurgic sciences.For Near East see Edgerton, 56 and Prasad, chapter IX. Greco-Roman world: Mondal, 2-3. The advent of the Mughals (established: April 21, 1526—ended: September 21, 1857) further improved the established tradition of metallurgy and metal working in India.Gommans (2002) During the period of British rule in India (first by the East India Company and then by the Crown), the metalworking industry in India stagnated due to various colonial policies, though efforts by industrialists led to the industry's revival during the 19th century.

Overview

Recent excavations in Middle Ganga Valley done by archaeologist Rakesh Tewari show iron working in India may have begun as early as 1800 BCE.e.g. R. Tewari 2003 Archaeological sites in India, such as Malhar, Dadupur, Raja Nala Ka Tila and Lahuradewa in the state of Uttar Pradesh show iron implements in the period between 1800 BCE – 1200 BCE. Sahi (1979: 366) concluded that by the early 13th century BCE, iron smelting was definitely practiced on a bigger scale in India, suggesting that the date the technology's inception may well be placed as early as the 16th century BCE. However, reviewing the claims of early uses of iron during c. 1800-1000 BCE, archaeologist Suraj Bhan noted, "the stratigraphical context and chronology of iron is not beyond doubt" at these sites (namely Malhar, Dadupur, and Lahuradeva) — although "there is no doubt" that iron was being used in the Ganges Plains "a few centuries before the rise of urbanization [...] around 600 BCE".

The Black and Red Ware culture was another early Iron Age archaeological culture of the northern Indian subcontinent. It is dated to roughly the 12th – 6th centuries BCE, and associated with the post-Rigvedic Vedic civilization. It extended from the upper Gangetic plain in Uttar Pradesh to the eastern Vindhya range and West Bengal.

Perhaps as early as 500 BCE, although certainly by 200 CE, high quality steel was being produced in southern India by what Europeans would later call the crucible technique. In this system, high-purity wrought iron, charcoal, and glass were mixed in crucibles and heated until the iron melted and absorbed the carbon. The resulting high-carbon steel, called fūlāḏ by the Arabs () and wootz by later Europeans, was exported throughout much of Asia and Europe.

Will Durant wrote in The Story of Civilization I: Our Oriental Heritage:

Hindu, Buddhist, Jain and other texts The Sanskrit term ayas means metal and can refer to bronze, copper or iron.

Rigveda

The Rigveda refers to ayas, and also states that the Dasyus had ayas (RV 2.20.8). In RV 4.2.17, "the gods [are] smelting like copper/metal ore the human generations".

The references to ayas in the Rig Veda probably refer to bronze or copper rather than to iron.(e.g. Frawley 1991) Scholars like Bhargava"Location of Brahmavarta and Drishadwati River is important to find earliest alignment of Saraswati River", Sudhir Bhargava, International Conference, 20–22 Nov. 2009, "Saraswati-a perspective" pages 114–117, Kurukshetra University, Kurukshetra, Organised by: Saraswati Nadi Shodh Sansthan, Haryana. maintain that Rigveda was written in the Vedic state of Brahmavarta and Khetri Copper mines formed an important location in Brahmavarta. Vedic people had used Copper extensively in agriculture, Water purification, tools, utensils etc., D. K. Chakrabarti (1992) argued: "It should be clear that any controversy regarding the meaning of ayas in the Rgveda or the problem of the Rgvedic familiarity or unfamiliarity with iron is pointless. There is no positive evidence either way. It can mean both copper-bronze and iron and, strictly on the basis of the contexts, there is no reason to choose between the two."

Arthashastra

The Arthashastra lays down the role of the Director of Metals, the Director of Forest Produce and the Director of Mining.Chakrabarti 1992 It is the duty of the Director of Metals to establish factories for different metals. The Director of Mines is responsible for the inspection of mines. The Arthashastra also refers to counterfeit coins.

Other texts

There are many references to ayas in the early Indian texts.A review of literary references to Ayas in the early Indian texts can be found in Chakrabarti 1996 and Chakrabarti 1992.

The Atharvaveda and the Shatapatha Brahmana refer to kṛṣṇa-ayas (), which could be iron (but possibly also iron ore and iron items not made of smelted iron). There is also some controversy if the term śyāma-ayas (), refers to iron or not. In later texts the term refers to iron. In earlier texts, it could possibly also refer to darker-than-copper bronze, an alloy of copper and tin.(Sethna 1992: 235) Copper can also become black when heated.Kazanas, Nicholas: Addendum to The AIT and Scholarship Oxidation with the use of sulphides can produce the same effect.In AV 11.3.7. Lohita (red copper) is compared with blood, and syama (swarthy metal) with flesh (maam-sa). This could be an analogy that describes how black metal (flesh) is produced by red metal (blood). Kazanas, Nicholas: Addendum to The AIT and Scholarship

The Yajurveda seems to know iron. In the Taittiriya Samhita are references to ayas and at least one reference to smiths. The Satapatha Brahmana 6.1.3.5 refers to the smelting of metallic ore.Chakrabarti 1996 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." Metal was also used in agriculture, and the Buddhist text Suttanipata has the following analogy: "for as a ploughshare that has got hot during the day when thrown into the water splashes, hisses and smokes in volumes..."

In the Charaka Samhita an analogy occurs that probably refers to the lost wax technique. The Silpasastras (the Manasara, the Manasollasa (Abhilashitartha Chintamani) and the Uttarabhaga of Silparatna) describe the lost wax technique in detail.

The Silappadikaram says that copper-smiths were in Puhar and in Madura. According to the History of the Han Dynasty by Ban Gu, Kashmir and "Tien-chu" were rich in metals.

The post-1400 CE treatise Rasaratnakara that deals with preparations of rasa (mercury) compounds. It gives a survey of the status of metallurgy and alchemy in the land. Extraction of metals such as silver, gold, tin and copper from their ores and their purification were also mentioned in the treatise. The Rasa Ratnasamuccaya describes the extraction and use of copper.

Archaeology

Chakrabarti (1976) has identified six early iron-using centres in India: Baluchistan, the Northwest, the Indo-Gangetic divide and the upper Gangetic valley, eastern India, Malwa and Berar in central India and the megalithic south India. The central Indian region seems to be the earliest iron-using centre.e.g., Cf. Chakrabarti 1992; Erdosy 1995

According to Tewari, iron using and iron "was prevalent in the Central Ganga Plain and the Eastern Vindhyas from the early 2nd millennium BC."Rakesh Tewari 2003

The evidence for smelted iron in Central India dates to 1300 to 1000 BCE.(see Bryant 2001: 246-248) These early findings also occur in places like the Deccan and the earliest evidence for smelted iron occurs in Central India, not in north-western India.(Bryant 2001: 246) Moreover, the dates for iron in India are not later than in those of Central Asia, and according to some scholars (e.g. Koshelenko 1986) the dates for smelted iron may actually be earlier in India than in Central Asia and Iran.(see Bryant 2001: 247) The Iron Age did however not necessary imply a major social transformation, and Gregory Possehl wrote that "the Iron Age is more of a continuation of the past then a break with it".cited in Bryant 2001

Recently reported claims of much earlier datings for iron smelting in Tamil Nadu's Sivagalai site are not yet published in peer-reviewed scientific journals and have been questioned by some scholars. Previously known early iron age sites in South India are Hallur, Karnataka and Adichanallur, Tamil NaduFront Page : Some pottery parallels. The Hindu (25 May 2007). Retrieved on 2013-07-12. at around 1000 BCE.Rakesh Tewari (2003), The origins of Iron-working in India: New evidence from the Central Ganga Plain and the Eastern Vindhyas. Archaeology Online. Agrawal et al. 1985: 228-29. Sahi (1979: 366)

Archaeological data suggests that India was "an independent and early centre of iron technology."Rakesh Tewari 2003; Chakrabarti 1976, 1992:171; Tripathi, Vibha. 2001; Erdosy 1995 According to Shaffer, the "nature and context of the iron objects involved [of the BRW culture] are very different from early iron objects found in Southwest Asia."Shaffer 1989, cited in Chakrabarti 1992:171 In Central Asia, the development of iron technology was not necessarily connected with Indo-Iranian migrations either.H. P. Francfort, Fouilles de Shortugai, Recherches sur L'Asie Centrale Protohistorique Paris: Diffusion de Boccard, 1989, p. 450

J.M. Kenoyer (1995) also remarks that there is a "long break in tin acquisition" necessary for the production of "tin bronzes" in the Indus Valley region, suggesting a lack of contact with Baluchistan and northern Afghanistan, or the lack of migrants from the north-west who could have procured tin.

Indus Valley Civilization

The copper-bronze metallurgy in the Harappan civilization was widespread and had a high variety and quality.Jim Shaffer 1992 "The Indus Valley, Baluchistan and Helmand Traditions: Neolithic Through Bronze Age." In Chronologies in Old World Archaeology. Second Edition. R.W. Ehrich, (Ed.). Chicago: University of Chicago Press. I:441-464, II:425-446., cited in Possehl 1992 The early use of iron may have developed from the practice of copper-smelting.Gregory Possehl, The Indus Civilization, 2002:94 While there is to date no proven evidence for smelted iron in the Indus Valley civilization, iron ore and iron items have been unearthed in eight Indus Valley sites, some of them dating to before 2600 BCE.(see Bryant 2001: 246-248, 339) There remains the possibility that some of these items were made of smelted iron, and the term "kṛṣṇa-ayas" might possibly also refer to these iron items, even if they are not made of smelted iron.

Lothali copper is unusually pure, lacking the arsenic typically used by coppersmiths across the rest of the Indus valley. Workers mixed tin with copper for the manufacture of celts, arrowheads, fishhooks, chisels, bangles, rings, drills and spearheads, although weapon manufacturing was minor. They also employed advanced metallurgy in following the cire perdue technique of casting, and used more than one-piece moulds for casting birds and animals.S. R. Rao, Lothal (ASI, 1985), pp. 42 They also invented new tools such as curved saws and twisted drills unknown to other civilizations at the time.S. R. Rao, Lothal (ASI, 1985), pp. 41-42

Metals

Copper Copper technology may date back to the 4th millennium BCE in the Himalaya region. It is the first element to be discovered in metallurgy, Copper and its alloys were also used to create copper-bronze images such as Buddhas or Hindu/Mahayana Buddhist deities. Xuanzang also noted that there were copper-bronze Buddha images in Magadha. In Varanasi, each stage of the image manufacturing process is handled by a specialist.Chakrabarti 1996, with reference to Mukherjee, M. 1978

Other metal objects made by Indian artisans include lamps. Copper was also a component in the razors for the tonsure ceremony.