The history of Tamil scripts is very rich and dates back to the period just after the Asokan era. The Tamil script is considered to have evolved from the Brahmi script. The initial Tamil inscriptions were constructed in Grantha, Brahmi and Vatteluttu scripts. Inscriptions that date after the 7th century AD have characters resembling the modern Tamil scripts. Thus some experts and scholar opine that vatteluttu and Tamil scripts instigated from Brahmi scripts. But, as there are elaborate descriptions of Tamil scripts provided in the Tolkappiyam, the earliest extant grammatical work in Tamil from the 3rd century BC, this argument lacks a concrete base. Tamil language had a distinctive script of its own even at earliest epoch. In fact, Vatteluttu is written in the ancient Tamil script.
The Tamil script is believed to have developed from the Brahmi script. The oldest inscriptions of Tamil writing date back to a period after the Asokan era. The script utilised by the inscriptions is usually called the Tamil Brahmi. Initially, Tamil Brahmi used different vowel markers and had extra characters to represent letters which are not found in Sanskrit. Moreover, letters for sounds not present in Tamil, like voiced consonants and aspirates, were omitted. Inscriptions from the 2nd century AD portray a later variety of the Tamil Brahmi script that is considerably similar to the writing system explained in the ancient Tamil grammar Tolkappiyam. The Tamil letters evolved gradually and during 5th century AD and 6th century AD, it adopted a form known as early vatteluttu.
In 7th century, new script for Tamil was created by the Pallava dynasty that was formed by simplifying the Grantha script. The vatteluttu letters were also added to it for sounds which are not available in Sanskrit. By the 8th century, the new script replaced vatteluttu in the Chola and Pallava kingdoms. Vatteluttu sustained to be utilised in the Chera and Pandyan kingdoms until the Pandyan kingdom was occupied by the Cholas in the 11th century. Over the course of time, the Chola-Pallava script advanced into the modern Tamil script. As palm leaves were used as the prime medium for writing, therefore several changes were made in the script accordingly.
The use of the pulli to differentiate pure consonants became uncommon, with pure consonants generally being written as if the inherent vowel were present. The vowel marker for the kurriyal ukaram, a half-rounded u which occurs at the end of some words and in the medial position in some compound words, also were not in use and was swapped by the marker for the simple u. after the introduction of printing, the pulli reappeared, but the kurriyal ukaram, a marker, was never put back into use, the sound still exists and has a vital role to play in the Tamil prosody.
The forms of few letters were uncomplicated in the 19th century to make the script easier to typescript. Further, in the 20th century, the Tamil script was simplified in a series of reforms. The vowel markers were regularized, which were used with consonants by removing special markers and most unbalanced forms.
