Megalithic graffiti symbols

In 1960, archaeologist B. B. Lal found that 89% of the surveyed megalithic symbols had their counterparts amongst the Indus script. He concluded that there was a commonness of culture between the Indus Valley Civilisation and the later megalithic period. In 2019, archaeologists in Tamil Nadu excavated further potsherds at Keeladi with graffiti closely resembling symbols of the Indus script.

From archaeological stratigraphy, potsherds with and without symbols are usually found at the lowest level, followed by potsherds with mixed symbols and Brahmi or Tamil Brahmi and eventually at the highest level potsherds are only found with Brahmi or Tamil Brahmi etchings. From around 300 CE, they disappear from grave sites. Scholars such as Iravatham Mahadevan have tried to link the symbols directly to Indus Valley script or as derived due to lingering influence, whereas others such as K. Rajan see the symbols as the genesis of the later Brahmi script. Yet many others see no particular alphabetic value in them only as graffiti symbols used for socio-religious purposes.