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. Metals Brass Brass was used in Lothal and Atranjikhera in the 3rd and 2nd millennium BCE. Brass and probably zinc was also found at Taxila in 4th to 3rd century BCE contexts. 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. Other metal objects made by Indian artisans include lamps. Copper was also a component in the razors for the tonsure ceremony. One of the most important sources of history in the Indian subcontinent 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