Br?hm? script refers to the oldest members of the Brahmic family of alphabets. The best known inscriptions in Br?hm? are the rock-cut edicts of Ashoka, dating to the 3rd century BCE. These were long considered the earliest examples of Br?hm? writing, but recent archaeological evidence in South India and Sri Lanka suggest the dates for the earliest use of Br?hm? to be around the 6th century BCE, dated using radiocarbon dating and thermoluminescence, though these dates are controversial.
This script was ancestral to most of the scripts of South Asia, Southeast Asia, Tibet, and perhaps even Korean Hangul. The Br?hm? numeral system was the ancestor of the Hindu-Arabic numerals, which are now used world-wide.
Connections between Phoenician and Brahmi.
Note that 6th- to 4th-century BCE Aramaic is in many cases intermediate in form between the two.
Indian-standard silver drachm of the Greco-Bactrian king Agathocles (190 BCE-180 BCE), the obverse showing the Greek legend BASILEOS AGATHOKLEOUS “Of King Agathocles”, the reverse RAJANE AGATHUKLAYASA “Of King Agathocles” in Br?hm?.
Br?hm? is clearly attested from the 3rd century BCE during the reign of Ashoka, who used the script for imperial edicts. It has commonly been supposed that the script was developed at around this time, both from the paucity of earlier dated examples, the alleged unreliability of those earlier dates, and from the geometric regularity of the script, which some have taken to be evidence that it had been recently invented. Recent claims for earlier dates include fragments of pottery from the trading town of Anuradhapura in Sri Lanka, which have been dated to the early 5th century BCE; discoveries in Bhattiprolu in Andhra Pradesh; and on pieces of pottery in Adichanallur, TamilNadu, which have been radio-carbon dated to the 6th century BCE.
Br?hm? is believed by most scholars to be derived from a Semitic script such as the Imperial Aramaic alphabet, as was clearly the case for the contemporary Kharosthi alphabet that arose in a part of northwest Indian under the control of the Achaemenid Empire. Rhys Davids suggests that writing may have been introduced to India from the Middle East by traders. Another possibility is with the Achaemenid conquest in the late 6th century BCE, or that it was a planned invention under Ashoka as a prerequiste for his edicts.
A glance at the oldest Br?hm? inscriptions shows striking parallels with contemporary Aramaic for the phonemes that are equivalent between the two languages, especially if the letters are flipped to reflect the change in writing direction. (Aramaic is written from right to left, as was Br?hm? originally, whereas Br?hm? later came to be written from left to right.) For example, both Br?hm? and Aramaic g resemble ?; both Br?hm? and Aramaic t resemble ?, etc.
Br?hm? script on stone Kanheri Caves
However, Semitic is not a good phonological match to Indic, so any Semitic alphabet would have needed extensive modification to represent Brahmi. Indeed, this is the most convincing circumstantial evidence for a link: The similarities between the scripts are just what one would expect from such an adaptation. For example, Aramaic did not distinguish dental from retroflex stops; in Br?hm? the dental and retroflex series are graphically very similar, as if both had been derived from a single prototype. Aramaic did not have Br?hm?’s aspirated consonants (kh, th), whereas Br?hm? did not have Aramaic’s emphatic consonants (q, ?, ?); and it appears that these emphatic letters were used for Br?hm?’s aspirates: Aramaic q for Br?hm? kh, Aramaic ? (?) for Br?hm? th (?). And just where Aramaic did not have a corresponding emphatic stop, p, Br?hm? seems to have doubled up for its aspirate: Br?hm? p and ph are graphically very similar, as if taken from the same source in Aramaic p. The first letters of the alphabets also match: Br?hm? a, which resembled a reversed ?, looks a lot like Aramaic alef, which resembled Hebrew ?.
According to others, Br?hm? was a purely indigenous development, perhaps with the Indus script as its predecessor; these include the English scholars G.R. Hunter and Raymond Allchin. In northern India, there is a gap of over one thousand years between the Indus script and Br?hm?, making an connection difficult, though it is possible this gap will be narrowed with future discoveries.
Some common variants of Brahmic letters
The Brahmi symbol for /ka/, modified to represent different vowels.Br?hm? is usually written from left to right, as in the case of its descendents. But a coin of the 4th century BC has been found inscribed with Br?hm? characters running from right to left. Br?hm? is an abugida, meaning that each letter represents a consonant, while vowels are written with obligatory diacritics. When no vowel is written, the vowel /a/ is understood. Special compound letters are used to write syllables that begin with consonant clusters, such as /pr/ or /rv/.
Br?hm? and its sister Kharoshthi are the two oldest alphabets of India. While Kharoshthi was only used in Afghanistan and northwestern India, Br?hm? was used across the Subcontinent. Over time, differing regional forms and styles of Brahmi developed into many descendant scripts. Kharoshthi, on the other hand, fell out of use without leaving any descendants.
Like Kharoshthi, Br?hm? was used to write the early dialects of Prakrit. Its usage was mostly restricted to inscriptions on buildings and graves as well as liturgical texts. The earlier Sanskrit had not been written down while it was natively spoken, and was only written many centuries later. As a result, Br?hm? is not a perfect match for Sanskrit, as several Sanskrit sounds have no letter or diacritic in Br?hm?.
Variants of Brahmi over time
Br?hm? evolved into many different scripts, which are commonly divided into a more rounded Southern India group and a more angular Northern India group. Over time, certain scripts became associated with specific languages. Alphabets of the Southern group spread into Southeast Asia, while the Northern group spread into Tibet. Today descendants of Br?hm? are used throughout India, Sri Lanka, Nepal, Bhutan, Tibet, Burma, Thailand, Laos, and scattered enclaves in Indonesia, southern China, southern Vietnam, and the Philippines. As the script of Buddhist scripture, Brahmic alphabets are used for religious purposes throughout China, Korea, and Japan, and Vietnam. Although controversial, it has been claimed that Hangul was based on a variant of the Tibetan alphabet used in the Mongol Empire.

Further reading

Kenneth R. Norman, The Development of Writing in India and its Effect upon the Pâli Canon, in Wiener Zeitschrift für die Kunde Südasiens,1993

Oscar von Hinüber, Der Beginn der Schrift und frühe Schriftlichkeit in Indien, Franz Steiner Verlag, 1990 (in German)

Gérard Fussman, Les premiers systèmes d’écriture en Inde, in Annuaire du Collège de France 1988-1989 (in French)

Siran Deraniyagala, The prehistory of Sri Lanka; an ecological perspective (revised ed.), Archaeological Survey Department of Sri Lanka, 1992