History of metallurgy in South Asia
The history of metallurgy in South Asia began prior to the 3rd millennium BCE and continued well into the British Raj. Metals and related concepts were mentioned in various early Vedic age texts. The Rigveda already uses the Sanskrit term Ayas (metal). The Indian cultural and commercial contacts with the Near East and the Greco-Roman world enabled an exchange of metallurgic sciences. With the advent of the Mughals, India's Mughal Empire (established: April 21, 1526—ended: September 21, 1857) further improved the established tradition of metallurgy and metal working in India.
The imperial policies of the British Raj led to stagnation of metallurgy in India as the British regulated mining and metallurgy—used in India previously by its rulers to build armies and resist England during various wars.
- 1 Overview
- 2 Hindu, Buddhist, Jain and other texts
- 3 Archaeology
- 4 Metals
- 5 Early History (—200 BCE)
- 6 Early Common Era—Early Modern Era
- 7 Colonial British Era—Republic of India
- 8 Further reading
- 9 See also
- 10 References
- 11 Terminology for ayas
- 12 External links
Recent excavations in Middle Ganga Valley done by archaeologist Rakesh Tewari show iron working in India may have begun as early as 1800 BCE. 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.
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 – 9th centuries BCE, and associated with the post-Rigvedic Vedic civilization. It reached from the upper Gangetic plain in Uttar Pradesh to the eastern Vindhya range and West Bengal.
Perhaps as early as 300 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 فولاذ in Arabic and wootz by later Europeans, was exported throughout much of Asia and Europe.
"Something has been said about the chemical excellence of cast iron in ancient India, and about the high industrial development of the Gupta times, when India was looked to, even by Imperial Rome, as the most skilled of the nations in such chemical industries as dyeing, tanning, soap-making, glass and cement... By the sixth century the Hindus were far ahead of Europe in industrial chemistry; they were masters of calcinations, distillation, sublimation, steaming, fixation, the production of light without heat, the mixing of anesthetic and soporific powders, and the preparation of metallic salts, compounds and alloys. The tempering of steel was brought in ancient India to a perfection unknown in Europe till our own times; King Porus is said to have selected, as a specially valuable gift from Alexander, not gold or silver, but thirty pounds of steel. The Moslems took much of this Hindu chemical science and industry to the Near East and Europe; the secret of manufacturing "Damascus" blades, for example, was taken by the Arabs from the Persians, and by the Persians from India."
Hindu, Buddhist, Jain and other texts
The references to Ayas in the Rig Veda probably refer to bronze or copper rather than to iron. However, 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."
The Arthasastra lays down the role of the Director of Metals, the Director of Forest Produce and the Director of Mining. 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 Arthasastra also refers to counterfeit coins.
There are many references to Ayas in the early Indian texts.
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). There is also some controversy if the term syamayas ("black metal) 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. Copper can also become black by heating it. Oxidation with the use of sulphides can produce the same effect.
The Yajurveda seems to know 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." 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[disambiguation needed]) and the Uttarabhaga of Silparatna) describe the lost wax technique in detail.
An influential Indian metallurgist and alchemist was Nagarjuna (born 931). He wrote the 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.
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.
The earliest evidence for smelted iron in India dates to 1300 to 1000 BCE. 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. 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. 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".
Archaeological data suggests that India was "an independent and early centre of iron technology." 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." In Central Asia, the development of iron technology was not necessarily connected with Indo-Iranian migrations either.
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. The early use of iron may have developed from the practice of copper-smelting. 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. There remains the possibility that some of these items were made of smelted iron, and the term "krsna 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. They also invented new tools such as curved saws and twisted drills unknown to other civilizations at the time.
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.
One of the most important sources of history in South Asia are the royal records of grants engraved on copper-plate grants (tamra-shasan or tamra-patra). Because copper does not rust or decay, they can survive indefinitely. Collections of archaeological texts from the copper-plates and rock-inscriptions have been compiled and published by the Archaeological Survey of India during the past century. The earliest known copper-plate known as the Sohgaura copper-plate is a Maurya record that mentions famine relief efforts. It is one of the very few pre-Ashoka Brahmi inscriptions in India.
Gold and silver
The deepest gold mines of the Ancient world were found in the Maski region in Karnataka. There were ancient silver mines in northwest India. Dated to the middle of the 1st millennium BCE. gold and silver were also used for making utensils for the royal family and nobilities.the royal family wore costly fabrics so it may be assumed that gold and silver were beaten into thin fibres and embroidered or woven into fabrics or dress.
Recent excavations in Middle Ganges Valley show iron working in India may have begun as early as 1800 BCE. In the 5th century BCE, the Greek historian Herodotus observed that "Indian and the Persian army used arrows tipped with iron." Ancient Romans used armour and cutlery made of Indian iron. Pliny the Elder also mentioned Indian iron. Muhammad al-Idrisi wrote the Hindus excelled in the manufacture of iron, and that it would be impossible to find anything to surpass the edge from Hindwani steel. Quintus Curtius wrote about an Indian present of steel to Alexander. Ferrum indicum appeared in the list of articles subject to duty under Marcus Aurelius and Commodus. Indian Wootz steel was held in high regard in Europe, and Indian iron was often considered to be the best.
Wootz and steel
The first form of crucible steel was wootz, developed in India some time around 300 BCE. In its production the iron was mixed with glass and then slowly heated and then cooled. As the mixture cooled the glass would bond to impurities in the steel and then float to the surface, leaving the steel considerably more pure. Carbon could enter the iron by diffusing in through the porous walls of the crucibles. Carbon dioxide would not react with the iron, but the small amounts of carbon monoxide could, adding carbon to the mix with some level of control. Wootz was widely exported throughout the Middle East, where it was combined with a local production technique around 1000 CE to produce Damascus steel, famed throughout the world. Wootz derives from the Kannada term for steel ukku. Indian wootz steel was the first high quality steel that was produced.
Henry Yule quoted the 12th-century Arab Edrizi who wrote: "The Hindus excel in the manufacture of iron, and in the preparations of those ingredients along with which it is fused to obtain that kind of soft iron which is usually styled Indian steel (Hindiah). They also have workshops wherein are forged the most famous sabres in the world. ...It is not possible to find anything to surpass the edge that you get from Indian steel (al-hadid al-Hindi).
As early as the 17th century, Europeans knew of India's ability to make crucible steel from reports brought back by travelers who had observed the process at several places in southern India. Several attempts were made to import the process, but failed because the exact technique remained a mystery. Studies of wootz were made in an attempt to understand its secrets, including a major effort by the famous scientist, Michael Faraday, son of a blacksmith. Working with a local cutlery manufacturer he wrongly concluded that it was the addition of aluminium oxide and silica from the glass that gave wootz its unique properties.
After the Indian rebellion of 1857, many Indian wootz steel swords were destroyed by order of the British authorities. Metal working suffered a decline during the British Empire, but steel production was revived in India by Jamsetji Tata.
Zinc was extracted in India as early as in the 4th to 3rd century BCE. Zinc production may have begun in India, and ancient northwestern India is the earliest known civilization that produced zinc on an industrial scale. The distillation technique was developed around 1200 CE at Zawar in Rajasthan.
In the 17th century, China exported Zinc to Europe under the name of totamu or tutenag. The term tutenag may derive from the South Indian term Tutthanagaa (zinc). In 1597, Libavius, a metallurgist in England received some quantity of Zinc metal and named it as Indian/Malabar lead. In 1738, William Champion is credited with patenting in Britain a process to extract zinc from calamine in a smelter, a technology that bore a strong resemblance to and was probably inspired by the process used in the Zawar zinc mines in Rajasthan. His first patent was rejected by the patent court on grounds of plagiarising the technology common in India. However, he was granted the patent on his second submission of patent approval. Postlewayt's Universal Dictionary of 1751 still wasn't aware of how Zinc was produced.
The Arthasastra describes the production of zinc. The Rasaratnakara by Nagarjuna describes the production of brass and zinc. There are references of medicinal uses of zinc in the Charaka Samhita (300 BCE). The Rasaratna Samuchaya (800 CE) explains the existence of two types of ores for zinc metal, one of which is ideal for metal extraction while the other is used for medicinal purpose. It also describes two methods of zinc distillation.
Early History (—200 BCE)
Recent excavations in Middle Ganges Valley conducted by archaeologist Rakesh Tewari show iron working in India may have begun as early as 1800 BCE. 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 early period may well be placed as early as the 16th century BCE.
Some of the early iron objects found in India are dated to 1400 BCE by employing the method of radio carbon dating. Spikes, knives, daggers, arrow-heads, bowls, spoons, saucepans, axes, chisels, tongs, door fittings etc. ranging from 600 BCE—200 BCE have been discovered from several archaeological sites. In Southern India (present day Mysore) iron appeared as early as the 12th or 11th century BCE. These developments were too early for any significant close contact with the northwest of the country.
The earliest available Bronze age swords of copper discovered from the Harappan sites in Pakistan date back to 2300 BCE. Swords have been recovered in archaeological findings throughout the Ganges-Jamuna Doab region of India, consisting of bronze but more commonly copper. Diverse specimens have been discovered in Fatehgarh, where there are several varieties of hilt. These swords have been variously dated to periods between 1700-1400 BCE, but were probably used more extensively during the opening centuries of the 1st millennium BCE.
The beginning of the 1st millennium BCE saw extensive developments in iron metallurgy in India. Technological advancement and mastery of iron metallurgy was achieved during this period of peaceful settlements. The years between 322—185 BCE saw several advancements being made to the technology involved in metallurgy during the politically stable Maurya period (322—185 BCE). Greek historian Herodotus (431—425 BCE) wrote the first western account of the use of iron in India.
Perhaps as early as 300 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 a crucible and heated until the iron melted and absorbed the carbon. The first crucible steel was the wootz steel that originated in India before the beginning of the common era. Wootz steel was widely exported and traded throughout ancient Europe, China, the Arab world, and became particularly famous in the Middle East, where it became known as Damascus steel. Archaeological evidence suggests that this manufacturing process was already in existence in South India well before the Christian era.
Zinc mines of Zawar, near Udaipur, Rajasthan, were active during 400 BCE. There are references of medicinal uses of zinc in the Charaka Samhita (300 BCE). The Rasaratna Samuccaya (800 CE) explains the existence of two types of ores for zinc metal, one of which is ideal for metal extraction while the other is used for medicinal purpose. The Periplus Maris Erythraei mentions weapons of Indian iron and steel being exported from India to Greece.
Early Common Era—Early Modern Era
The world's first iron pillar was the Iron pillar of Delhi—erected at the times of Chandragupta II Vikramaditya (375–413). The swords manufactured in Indian workshops find written mention in the works of Muhammad al-Idrisi (flourished 1154). Indian Blades made of Damascus steel found their way into Persia. European scholars—during the 14th century—studied Indian casting and metallurgy technology.
Indian metallurgy under the Mughal emperor Akbar (reign: 1556-1605) produced excellent small firearms. Gommans (2002) holds that Mughal handguns were stronger and more accurate than their European counterparts.
Akbar reformed Mughal currency to make it one of the best known of its time. The new regime possessed a fully functioning trimetallic (silver, copper, and gold) currency, with an open minting system in which anyone willing to pay the minting charges could bring metal or old or foreign coin to the mint and have it struck. All monetary exchanges were, however, expressed in copper coins in Akbar's time. In the 17th century, following the silver influx from the New World, silver rupee with new fractional denominations replaced the copper coin as a common medium of circulation. Akbar's aim was to establish a uniform coinage throughout his empire; some coins of the old regime and regional kingdoms also continued.
Statues of Nataraja and Vishnu were cast during the reign of the imperial Chola dynasty (200-1279) in the 9th century. The casting could involve a mixture of five metals: copper, zinc, tin, gold, and silver.
Considered one of the most remarkable feats in metallurgy, the Seamless[disambiguation needed] celestial globe was invented in Kashmir by Ali Kashmiri ibn Luqman in 998 AH (1589-90 CE), and twenty other such globes were later produced in Lahore and Kashmir during the Mughal Empire. Before they were rediscovered in the 1980s, it was believed by modern metallurgists to be technically impossible to produce metal globes without any seams, even with modern technology. These Mughal metallurgists pioneered the method of lost-wax casting in order to produce these globes.
Colonial British Era—Republic of India
With the partial exception of coal, foreign competition, aided by the absence of tariff barriers and lack of technological innovation, held back the development of mining and metal-working technology in India until the early 20th century. The relatively crude, labour-intensive nature of surviving mining techniques contributed to the false impression that India was poorly endowed with mineral resources or that they were inaccessible or otherwise difficult and unremunerative to work. But the fate of mining and metallurgy was affected by political as well as by economic and technological considerations.
The British were aware of the part metal-working had played in supporting indigenous powers in the past through the production of arms and ammunition, and, just as they introduced an Arms Act in 1878 to restrict Indian access to firearms, so they sought to limit India’s ability to mine and work metals that might sustain it in future wars and rebellions. This was especially the case with Rajasthan, a region rich in metals. In the 1820s James Tod identified the ‘mines of Mewar’ as one of the means that had enabled its masters ‘so long to struggle against superior power, and to raise those magnificent structures which would do honour to the most potent kingdoms of the west’. Indian skill in the difficult art of casting brass cannon had made Indian artillery a formidable adversary from the reign of Akbar to the Maratha and Sikh wars 300 years later. But by the early 19th century most of the mines in Rajasthan had been abandoned: the caste of miners was ‘extinct’.
During the Company period, as military opponents were eliminated and princely states extinguished, so was the local capacity to mine and work metals steadily eroded. As late as the Rebellion of 1857, the mining of lead for ammunition at Ajmer was perceived as a threat the British would no longer countenance and the mines were closed down.
The first iron-cased and metal-cylinder rockets were developed by Tipu Sultan, ruler of the South Indian Kingdom of Mysore, and his father Hyder Ali, in the 1780s. He successfully used these iron-cased rockets against the larger forces of the British East India Company during the Anglo-Mysore Wars.
- Agarwal, D.P. 2000. Ancient Metal Technology and Archaeology of South Asia. New Delhi: Aryan Books International. ISBN 81-7305-177-1
- Biswas, Arun Kumar. 1994. Minerals and Metals in Ancient India. Vol. 1 Archaeological Evidence. New Delhi: D. K. Printworld (P) Ltd.  
- Dilip K. Chakrabarti. The Early use of Iron In India. 1992. New Delhi: The Oxford University Press. 
- Chakrabarti D.K. (1996a). Copper and its Alloys in Ancient India. Delhi: Munshiram Manoharlal Publishers Private Limited
- Mukherjee, M. 1978 Metalcraftsmen of India, Calcutta
- Rakesh Tewari, 2003, The origins of iron-working in India: new evidence from the Central Ganga Plain and the Eastern Vindhyas
- Srinivasan, Sharda and Srinivasa Rangnathan. 2004. India’s Legendary Wootz Steel. Bangalore: Tata Steel.  
- Tripathi, Vibha (Ed.). 1998. Archaeometallurgy in India. Delhi: Sharada Publishing House. 
- Tripathi, Vibha. 2001. The Age of Iron in India. New Delhi: Aryan Books International. 
- Allchin, F.R. (1979), South Asian Archaeology 1975: Papers from the Third International Conference of the Association of South Asian Archaeologists in Western Europe, Held in Paris edited by J.E.van Lohuizen-de Leeuw, Brill Academic Publishers, ISBN 90-04-05996-2.
- Arnold, David (2004), The New Cambridge History of India: Science, Technology and Medicine in Colonial India, Cambridge University Press, ISBN 0-521-56319-4.
- Balasubramaniam, R. (2002), Delhi Iron Pillar: New Insights, Indian Institute of Advanced Studies, ISBN 81-7305-223-9.
- Ceccarelli, Marco (2000), International Symposium on History of Machines and Mechanisms: Proceedings HMM Symposium, Springer, ISBN 0-7923-6372-8.
- Craddock, P.T. etc. (1983). "Zinc production in medieval India", World Archaeology, 15 (2), Industrial Archaeology.
- Drakonoff, I. M. (1991), Early Antiquity, University of Chicago Press, ISBN 0-226-14465-8.
- Edgerton etc. (2002), Indian and Oriental Arms and Armour, Courier Dover Publications, ISBN 0-486-42229-1.
- Gommans, Jos J. L. (2002), Mughal Warfare: Indian Frontiers and Highroads to Empire, 1500-1700, Routledge, ISBN 0-415-23989-3.
- Juleff, G. (1996), "An ancient wind powered iron smelting technology in Sri Lanka", Nature, 379 (3): 60–63.
- Mondal, Biswanath (2004), Proceedings of the National Conference on Investment Casting: NCIC 2003, Allied Publishers, ISBN 81-7764-659-1.
- Prasad, P. C. (2003), Foreign Trade and Commerce in Ancient India, Abhinav Publications, ISBN 81-7017-053-2.
- Richards, J. F. etc. (2005), The New Cambridge History of India, Cambridge University Press, ISBN 0-521-36424-8.
- Savage-Smith, Emilie (1985), Islamicate Celestial Globes: Their History, Construction, and Use, Smithsonian Institution Press.
- Srinivasan, S. & Ranganathan, S., Wootz Steel: An Advanced Material of the Ancient World, Indian Institute of Science.
- Srinivasan, S. (1994), Wootz crucible steel: a newly discovered production site in South India, Institute of Archaeology, University College London, 5: 49-61.
- Srinivasan, S. and Griffiths, D., South Indian wootz: evidence for high-carbon steel from crucibles from a newly identified site and preliminary comparisons with related finds, Material Issues in Art and Archaeology-V, Materials Research Society Symposium Proceedings Series, Vol. 462.
- Srivastava, A.L. & Alam, Muzaffar (2008), India, Encyclopædia Britannica.
- Tewari, Rakesh (2003), "The origins of Iron Working in India: New evidence from the Central Ganga plain and the Eastern Vindhyas", Antiquity, 77: 536-544.
- P. Yule–A. Hauptmann–M. Hughes. 1989 . The Copper Hoards of the Indian Subcontinent: Preliminaries for an Interpretation, Jahrbuch des Römisch-Germanischen Zentralmuseums Mainz 36, 193–275, ISSN 0076-2741 = http://archiv.ub.uni-heidelberg.de/savifadok/volltexte/2009/509/
- Damascus steel
- Wootz steel
- Crucible steel
- Iron pillar of Delhi
- Copper-plate grant
- Iron Age India, Iron Age
- Indian coinage
- Science and technology in ancient India
- See Tewari (2003) and Arnold, 100-101.
- For Near East see Edgerton, 56 and Prasad, chapter IX. Greco-Roman world: Mondal, 2-3.
- Gommans (2002)
- Arnold, 100-101
- e.g. R. Tewari 2003
- Origins of Iron Ore
- (e.g. Frawley 1991)
- Chakrabarti 1992
- A review of literary references to Ayas in the early Indian texts can be found in Chakrabarti 1996 and Chakrabarti 1992.
- (Sethna 1992: 235)
- Agarwal, Vishal (2003), "A Reply to Michael Witzel’s ‘Ein Fremdling im Rgveda’" (PDF), Journal of Indo-European Studies 31 (1-2): 107–185
- Kazanas, Nicholas: Addendum to The AIT and Scholarship
- 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
- Chakrabarti 1996
- Copper Technology in the Central Himalayas Goes Back to 2000BC
- e.g., Cf. Chakrabarti 1992; Erdosy 1995
- Rakesh Tewari 2003
- (see Bryant 2001: 246-248)
- (Bryant 2001: 246)
- (see Bryant 2001: 247)
- cited in Bryant 2001
- Rakesh Tewari 2003; Chakrabarti 1976, 1992:171; Tripathi, Vibha. 2001; Erdosy 1995
- Shaffer 1989, cited in Chakrabarti 1992:171
- H. P. Francfort, Fouilles de Shortugai, Recherches sur L'Asie Centrale Protohistorique Paris: Diffusion de Boccard, 1989, p. 450
- 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
- Gregory Possehl, The Indus Civilization, 2002:94
- (see Bryant 2001: 246-248, 339)
- S. R. Rao, Lothal (ASI, 1985), pp. 42
- S. R. Rao, Lothal (ASI, 1985), pp. 41-42
- The Bill of Contentions
- Craddock et al. 1983
- Chakrabarti 1996, with reference to Mukherjee, M. 1978
- They date to the middle of the 1st millennium BCE. Srinivasan, Sharda and Srinivasa Rangnathan. 2004
- Tewari (2003)
- Srinivasan, Sharda and Srinivasa Rangnathan. 2004
- Srinivasan, Sharda and Srinivasa Rangnathan. 2004; W. Egerton, Indian and Oriental Armour, London (1896).
- J.M. Heath 1839, quoted by Chakrabarti 1992; G. N. Pant, Indian Arms and Armour, Vol. I and II, National Museum, New Delhi (1980)
- e.g. James Stodart 1818, Robert Hadfield, quoted by Chakrabarti 1992:3-6, 119; Robert Hadfield, Sinhalese iron and steel of ancient origin, Journal of the Iron and Steel Institute, 85 (1912).
- C. S. Smith, A History of Metallography, University Press, Chicago (1960); Juleff 1996; Srinivasan, Sharda and Srinivasa Rangnathan 2004
- Craddock et al. 1983. (The earliest evidence for the production of zinc comes from India. Srinivasan, Sharda and Srinivasa Rangnathan. 2004)
- India Was the First to Smelt Zinc by Distillation Process
- Arun Kumar Biswas, Zinc and related alloys
- TKS Book Series
- ; Srinivasan, Sharda and Srinivasa Rangnathan. 2004
- Ceccarelli, 218
- Drakonoff, 372
- Allchin, 111-114
- Richards etc., 64
- Juleff 1996
- Srinivasan & Ranganathan
- Srinivasan 1994
- Srinivasan & Griffiths
- Craddock (1983)
- Prasad, chapter IX
- Balasubramaniam, R. (2002)
- Edgerton, 56
- Mondal, 2-3
- Gommans, 154
- Gommans, 155
- Srivastava & Alam (2008)
- Savage-Smith (1985)
- "Hyder Ali, prince of Mysore, developed war rockets with an important change: the use of metal cylinders to contain the combustion powder. Although the hammered soft iron he used was crude, the bursting strength of the container of black powder was much higher than the earlier paper construction. Thus a greater internal pressure was possible, with a resultant greater thrust of the propulsive jet. The rocket body was lashed with leather thongs to a long bamboo stick. Range was perhaps up to three-quarters of a mile (more than a kilometre). Although individually these rockets were not accurate, dispersion error became less important when large numbers were fired rapidly in mass attacks. They were particularly effective against cavalry and were hurled into the air, after lighting, or skimmed along the hard dry ground. Hyder Ali's son, Tippu Sultan, continued to develop and expand the use of rocket weapons, reportedly increasing the number of rocket troops from 1,200 to a corps of 5,000. In battles at Seringapatam in 1792 and 1799 these rockets were used with considerable effect against the British." - Encyclopædia Britannica (2008), rocket and missile.
- Edwin Bryant (2001). The Quest for the Origins of Vedic Culture: The Indo-Aryan Migration Debate. Oxford University Press. ISBN 0-19-516947-6.
- Craddock, P.T. et al., Zinc production in medieval India, World Archaeology, vol.15, no.2, Industrial Archaeology, 1983
- G. Juleff, "An ancient wind powered iron smeting technology in Sri Lanka", Nature 379 (3), 60-63 (January 1996)
- Erdosy, George: 1995; "The Prelude to urbanization", in The Archaeology of the Early Historic South Asia: The Emergence of cities and states. Allchin, F. R. et al. (eds.), Cambridge 1995.
- Frawley, David (1995). Gods, Sages and Kings. 1991.Lotus Press, Twin Lakes, Wisconsin ISBN 0-910261-37-7
- Kenoyer, J.M. (1995). Interaction Systems, Specialized crafts and Culture Change. In: Indo-Aryans of Ancient South Asia. Ed. George Erdosy.. ISBN 3110144476
- Sethna, K.D. 1992. The Problem of Aryan Origins. New Delhi: Aditya Prakashan. ISBN 81-85179-67-0
- S. R. Rao, Lothal (published by the Director General, Archaeological Survey of India, 1985)
- Shaffer, Jim. Mathura: A protohistoric Perspective in D.M. Srinivasan (ed.), Mathura, the Cultural Heritage, 1989, pp. 171–180. Delhi.
- J.D. Verhoeven, A.H. Pendray, and W.E. Dauksch. (1998). The Key Role of Impurities in Ancient Damascus Steel Blades. Journal of Metals. 50(9). pp. 58–64. 
- Lynn Willies et al. 1984, Ancient Zinc and Lead Mining in Rajasthan, India. World Archaeology, Vol.16, No. 2, Mines and Quarries.
Terminology for ayas
- Prastarika: metal trader
- Sulbhadhatusastra: science of metals
- panchaloha, sarva loha: the five base metals (tin, lead, iron, copper, silver)
- The origins of Iron-working in India
- Copper Technology in the Central Himalayas Dates Back to 2000 BCE
- TKS Metallurgy Bibliography
- Zinc production in Ancient India 
- Wootz steel: an advanced material of the ancient world
- Indian heritage in metallurgy
- Zinc and related alloys
- Smelting of Zinc by Distillation Process
- Iron In Kumaun Goes Back To First Millennium BC D.P. Agrawal and Manikant Shah