How Sargam or Seven Notes of Indian Music Originated?

The initial notes in Indian music were three viz. udatta, anudatta and svarita. The Samaveda employed more notes and thus finally settled down on seven notes, which were krusht, pratham, dwitiya, tritiya, chaturth, mandra and atiswār. This later evolved into what we call the seven Svaras.

The seven Svaras are the basic notes of an octave named Ṣaḍjaṃ, Riṣabh, Gāndhār, Madhyam, Pañcham, Dhaivata and Niṣād (Sa Re Ga Ma Pa Dha and Ni) respectively. Collectively, they are called Sargam. A series of the seven notes is also known as