The Brahmi writing system was being used in the Indian subcontinent in the third century BC. It was probably created through the efforts of Emperor Ashoka of Mauryan Dynasty who ruled from 268 to 232 BC. He was the first emperor to rule over almost the entire South Asia—a densely populated area as large as Western Europe, stretching from present-day Afghanistan in the west to Bangladesh in the east, and covering much of central India. He ruled from Pataliputra (present day Patna), and had provincial capitals in Taxila (a city in present day Pakistan) and Ujjain (in Madhya Pradesh).
Several of Ashoka’s rock edicts, which are spread throughout modern-day Pakistan and India, are written in Brahmi script, which has influenced the Sanskrit-based languages that are currently being used in North India and the four Dravidian languages that are being used in South India. The languages in Southeast Asia are also influenced by Brahmi. However, over the centuries, these languages have transformed so much that their connection to a common Brahmi language is not easily detected. The Brahmi script was deciphered in the 1830s by James Prinsep.
There are a number of theories about the origin of the Brahmi script. Some scholars have suggested that the Brahmi script was developed from the Semitic script via Aramaic. But there are other scholars who insist that the Brahmi script comes from Indian sources. Several attempts have been made to connect the Brahmi script with the Indus script, but the connection between the two writing systems is not clear, since the Indus script remains undeciphered. The theory that I find plausible is that Brahmi was created when Ashoka ordered his officials to create a writing system based on the existing sources in India. His officials could have used the system of record keeping then used by Indian merchants to develop the Brahmi script.
The sounds in Brahmi script match the sounds of Pali and other popular Indic languages which are founded on Sanskrit. Pali is the language in which Buddha has preached. A number of Ashoka’s rock inscriptions are in Pali.