The earliest undisputed deciphered epigraphy found in the Indian subcontinent are the Edicts of Ashoka of the 3rd century BCE, in the Brahmi script. If epigraphy of proto-writing is included, undeciphered markings with symbol systems that may or may not contain linguistic information, there is substantially older epigraphy in the Indus script, which dates back to the early 3rd millennium BCE. Two other important archeological classes of symbols are found from the 1st millennium BCE, Megalithic graffiti symbols and symbols on punch-marked coins, though most scholars do not consider these to constitute fully linguistic scripts, and their semiotic functions are not well understood. Writing in Sanskrit (Epigraphical Hybrid Sanskrit, EHS) appears in the 1st to 4th centuries CE. Indian epigraphy becomes more widespread over the 1st millennium, engraved on the faces of cliffs, on pillars, on tablets of stone, drawn in caves and on rocks, some gouged into the bedrock. Later they were also inscribed on palm leaves, coins, Indian copper plate inscriptions, and on temple walls. Many of the inscriptions are couched in extravagant language, but when the information gained from inscriptions can be corroborated with information from other sources such as still existing monuments or ruins, inscriptions provide insight into India's dynastic history that otherwise lacks contemporary historical records. Of the c. 100,000 inscriptions found by the Archaeological Survey of India, about 60,000 were in Tamil Nadu. First appearance of writing in the Indian Subcontinent The Bronze Age Indus script remains undeciphered and may not actually represent a writing system. Hence, the first undisputed evidence of writing in the South Asian Subcontinent are the Edicts of Ashoka from c. 250 BCE. Several inscriptions were thought to be pre-Ashokan by earlier scholars; these include the Piprahwa relic casket inscription, the Badli pillar inscription, the Bhattiprolu relic casket inscription, the Sohgaura copper plate inscription, the Mahasthangarh Brahmi inscription, the Eran coin legend, the Taxila coin legends, and the inscription on the silver coins of Sophytes. However, more recent scholars have dated them to later periods. Until the 1990s, it was generally accepted that the Brahmi script used by Ashoka spread to South India during the second half of the 3rd century BCE, assuming a local form now known as Tamil-Brahmi. Beginning in the late 1990s, archaeological excavations have produced a small number of candidates for Brahmi epigraphy predating Ashoka. Preliminary press reports of such pre-Ashokan inscriptions have appeared over the