The Brahmi script was originally written from left to right, although early inscription
s on monuments have been found written from right to left. Brahmi spread across India, used to write many languages in the Southern portion of the continent and came into use in such places as Sri Lanka
and countries of Southeast Asia. Modifications to fit local pronunciations and morphemes eventually allowed the evolution of several derived scripts, such as Devanagari
, and dozens of other local scripts. These are classified into two basic categories of 'northern' scripts and 'southern' scripts, with distinctive morphology marking off their categorization. The split began in about the first century CE
A distinctive characteristic of all Brahmi derived scripts is their use of a 'head' in some way. The head was originally found in Brahmi because of use of a reed pen, which created straight lines between each letter of the word even though they were written individually. This head is still reflected in such features as the straight line connection of Devanagarai, the check-mark at the top of Kannada, and the umbrella-like diacritic connecting letters of Oriya.
There are currently two camps regarding the development of Brahmi. One insists that it is a distant derivitive of a Semitic script such as Aramaic or Phoenician (similar to a related Indian script, Kharoshthi). As an alphasyllabary, or abugida, certain distinctive connections can be drawn between the consonant syllabic qualities of early Semitic scripts and Brahmi, as well as the association between the shapes of symbols representing certain common morphemes. The jury is still out, however.
Information sourced from Daniels, Peter T. Bright, William. The World's Writing Systems. Oxford: Oxford University Press, 1996.