Brahmic scripts are descended from the Brahmi script. Brahmi is clearly attested from the 3rd century BC during the reign of Ashoka, who used the script for imperial edicts, but there are some claims of earlier epigraphy found on pottery in South India and Sri Lanka. The most reliable of these were short Brahmi inscriptions dated to the 4th century BCE and published by Coningham et al., but scattered press reports have claimed both dates as early as the 6th century BCE and that the characters are identifiably Tamil Brahmi, though these latter claims do not appear to have been published academically.[dubious– discuss] Northern Brahmi gave rise to the Gupta script during the Gupta period, which in turn diversified into a number of cursives during the Middle Ages, including Siddham, Sharada and Nagari.
Some characteristics, which may not be present in all the scripts, are:
Each consonant has an inherent vowel which is usually short 'a' (in Bengali, and Assamese, it is short 'ô' due to sound shifts). Other vowels are written by adding to the character. A mark, known in Sanskrit as a virama/halant can be used to indicate the absence of an inherent vowel.
Each vowel has two forms, an independent form when not part of a consonant, and a dependent form, when attached to a consonant. Depending on the script, the dependent forms can be either placed to the left of, to the right of, above, below, or on both the left and the right sides of the base consonant.
Consonants (up to 4 in Devanagari) can be combined in ligatures. Special marks are added to denote the combination of 'r' with another consonant.
Below are comparison charts of several of the major Indic scripts, organised on the principle that glyphs in the same column all derive from the same Brahmi glyph. Accordingly:
The charts are not comprehensive. Glyphs may be unrepresented if they don't derive from any Brahmi character, but are later inventions.
The pronunciations of glyphs in the same column may not be identical. The pronunciation row is only representative; the International Phonetic Alphabet (IPA) pronunciation is given for Sanskrit where possible, or another language if necessary.
Vowels are presented in their independent form on the left of each column, and in their corresponding dependent form (vowel sign) combined with the consonant k on the right. A glyph for ka is an independent consonant letter itself without any vowel sign, where the vowel a is inherent. When used to write their own languages, Khmer and Thai script can have either an a or an o as the inherent vowel, following the rules of their respective orthographies. Thai and Lao script do not have independent vowel forms, for syllables starting with a vowel sound, a zero consonant, อ and ອ respectively, is used as a placeholder.
The Brahmi script was already divided into regional variants at the time of the earliest surviving epigraphy around the 3rd century BCE. Cursives of the Brahmi script began to diversify further from around the 5th century CE and continued to give rise to new scripts throughout the Middle Ages. The main division in antiquity was between northern and southern Brahmi. In the northern group, the Gupta script was very influential, and in the southern group the Vatteluttu and Old-Kannada/Pallava scripts with the spread of Hinduism sent Brahmic scripts throughout Southeast Asia.