Origins of Iron Working in Indiahttp://archaeologyonline.net/artifacts/iron-ore
The date and origin of the introduction of iron artefacts and iron working into India has remained a much debated research problem, not unconnected with the equally debatable question of its association with the supposed arrival, in the second millennium BCE, of immigrants from the west, as often suggested on the basis of the Rigveda. Around the middle of the last century, iron-working origins in India were dated to c. 700-600 BCE (Gordon 1950; Wheeler 1959). Subsequently, a combination of an association with Painted Grey Ware (PGW) and the advent of radiocarbon dating began to push this date back towards the second millennium BCE, a period which had in fact favoured by some scholars earlier in the early twentieth century (Chakrabarti 1992: 10-12).
These results indicate that iron using and iron working was prevalent in the Central Ganga Plain and the Eastern Vindhyas from the early second millennium BCE. The dates obtained so far group into three: three dates between c. 1200-900 cal BCE, three between c. 1400-1200 cal BCE, and five between c. 1800-1500 cal BCE. The types and shapes of the associated pottery are comparable to those to be generally considered as the characteristics of the Chalcolithic Period and placed in early to late second millennium BCE. Taking all this evidence together it may be concluded that knowledge of iron smelting and manufacturing of iron artefacts was well known in the Eastern Vindhyas and iron had been in use in the Central Ganga Plain, at least from the early second millennium BCE. The quantity and types of iron artefacts, and the level of technical advancement indicate that the introduction of iron working took place even earlier. The beginning of the use of iron has been traditionally associated with the eastward migration of the later Vedic people, who are also considered as an agency which revolutionised material culture particularly in eastern Uttar Pradesh and Bihar (Sharma 1983: 117-131). The new finds and their dates suggest that a fresh review is needed. Further, the evidence corroborates the early use of iron in other areas of the country, and attests that India was indeed an independent centre for the development of the working of iron.
Set of iron age is considered very crucial as everything high-tech is attributed to set of iron age. Worst is that archaeologists of reputed universities and institutes do not update themselves and keep telling students that iron was first used in India in 600-700 BCE.
Off late, interacting with archaeologists. They still date rigveda to the max mullerian date of 1500 BCE and discuss about vedic and post vedic india which is hilarious. It is also a part of seal-a-bus (of lies). Those archaeologists who hold the view that everything to India came from West Asia or sometimes South east Asia are called "Diffusionists" and are ashamed of asserting their Indianness. Though many with whom I have interacted are quoting anthropological studies that concept of Aryan and Dravidian as races is pure BS. Anthropological studies have already discarded Aryan and Dravidians as any kind of racial thing.
Even after telling them that there are now ample evidences that Saraswati dried gradually by 1900 BCE and references in Veda are there about saraswati flowing to the ocean automatically predates max mullerian dates, they still wonder and deny. Cognitive Dissonance.