Probably the greatest change to Indian music happened during the reign of the Persian Moghul Akbar under the court musician Mien Tansen. His Persian influence fundamentally changed Northern Indian music 500 years ago. Although nobody is sure exactly when the split occurred between North and South Indian music, the influence of Tansen would have separated the two systems completely. He ascribed the names Hindustani to North Indian and Carnatic to South Indian music. To describe the differences, one needs a basic understanding of Indian music.
Many people think of the raga as the scale.
However, the raga is much more than that. In Carnatic music there are 72 that5. These seven note scales are much like western scales, based on combinations of the twelve semi-tones of the octave, with the first and fifth note invariant. Actually, in India, the octave is divided into 22 notes, however, ten of these are treated as passing or grace notes, and the twelve semi-tones are used predominantly. The sitar, veena and other fretted instruments have 12 semi-tone frets per octave.