Theory

Origin of Indian Music - It is believed that Indian Music originated from Vedas at unknown time. One of the four Vedas 'Samveda' shlokas were sung in musical notes.
Shruti - Human recognisable 22 notes were identified in an Octave but due to extreme difficulty in recognising these Shrutis, only 12 Notes or Swara were finally used for singing or playing.  These are: Sa    re    Re     ga     Ga       Ma       Ma'        Pa         dha         Dha        ni         Ni