THE EARLIEST HINDU LANGUAGE DECIPHERED THROUGH GREEK ~ BRAHMI SCRIPT

The earliest,undisputedly dated, and best-known Brahmi inscriptions are the rock-cut edicts of Ashoka in north-central India, dating to 250–232 BCE.

From 1834, some attempts were made to decipher the Brahmi script, the main script used in old Indian inscriptions such as the Edicts of Ashoka, and which had become extinct since the 5th century CE. Some attempts by Rev. J. Stevenson were made to identify characters from the Karla Caves (circa 1st century CE), based on their similarities with the Gupta script of the Samudragupta inscription of the Allahabad pillar (3th century CE) which had just been deciphered, but this led to a mix of good (about 1/3) and bad guesses, which did not permit proper deciphering of the Brahmi.

The first successful attempts at deciphering the ancient Brahmi script of the 3rd-2nd centuries BCE were made in 1836 by Norwegian scholar Christian Lassen, who used the bilingual Greek-Brahmi coins of  Indo-Greek kings Agathocles and Pantaleon to correctly and securely identify several Brahmi letters. 

The task was then completed by James Prinsep, an archaeologist, philologist, and official of the East India Company, who was able to identify the rest of the Brahmi characters, with the help of Major Cunningham. In a series of results that he published in March 1838, Prinsep was able to translate the inscriptions on a large number of rock edicts found around India, and provide, according to Richard Salomon, a "virtually perfect" rendering of the full Brahmi alphabet.

SOURCE: Wikipedia