Invention of writing, ca. 3500 BCE complemented the inventions of the bronze-age in India. A writing system which functioned for trade from Meluhha region, called Indus script, contains many artistic representations which continued as an art tradition in historic periods, evidenced on devices used on punch-marked coins. The determination of the function and meanings of the glyphs used in the script is made possible by identifying the glyphs as hieroglyphs composed of all pictorial motifs -- over 100 -- and signs -- over 400 - and read rebus in mleccha vācas (as distinct from arya vācas - both language categories mentioned by Manu). The context is: miners' and smiths' repertoire [not unlike the viśwakarma (metalworking artisans) working on bronze images in Swamimalai (Tamil Nadu, India) following the cire perdue technique of Sarasvati civilization bronzes or asur/agaria working in iron ore smelters in Ganga basin of 18th century BCE]. Indian hieroglyphs are in mleccha (cognate Meluhha), mlecchita vikalpa (Vatsyayana). Hypothesis posited: Language X + Proto-Munda = Proto-mleccha (with borrowings into Indo-Aryan and Dravidian languages, constituting Indian sprachbund.