bhirrana period 1a dated 7500 BC to 6000 BC crucible fragments with molten copper। copper arrowhead bhirrana period 1b dated 6000 BC to 4500 BC see plate 31 page numbered 24 for image।https://www.scribd.com/document/260613722/Origin-of-Early-Harappan-Cultures-in-the-Sarasvati-Valley-Recent-Archaeological-Evidence-and-Radiometric-Dates। lost wax casting technique from mehrgarh period 3 dated 4500 BC to 3600 BC।https://www.nature.com/articles/ncomms13356। copper arrowhead at lahuradewa period 1b 3000 BC to 2000 BC image on page 41।https://www.researchgate.net/publication/285330785_Second_preliminary_report_of_the_excavations_at_Lahuradewa_District_Sant_Kabir_Nagar_UP_2002-04_and_2005-06। iron arrowhead dadupur period 1 lucknow 1700 BC image on page 7।http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.403.4300&type=pdfhttp://archaeologyonline.net/artifacts/iron-ore। copper arrowhead kultepe 1 nakhchivan azerbaijan 4600 BC page 594 fig 22.8।https://www.academia.edu/5789550/2014_-_Ancient_Metallurgy_in_the_Caucasus_From_the_Sixth_to_the_Third_Millennium_BCEhttps://en.m.wikipedia.org/wiki/File:Exponates_from_K%C3%BCltepe_I_(Azerbaijan)_3.jpg। copper arrowhead tepe hissar iran 2500 BC।https://www.penn.museum/collections/object/91279। copper swords at arslantepe royal tomb 3300 BC to 3100 BC।https://www.tf.uni-kiel.de/matwis/amat/iss/kap_b/backbone/rb_1_1.html। copper sword at sinauli baghpat 2300 BC to 1950 BC।https://mobile.twitter.com/sanjeevsanyal/status/1097140890785771520