Around the 5th century, Bharata wrote a theoretical book on drama, dance, and music - "Nathya Shastri", which connected ancient Indian music with Indian classical music. Together with the important theoretical achievements, the germ of the earliest Brahmanical classical music can still be seen. "Natheya Shastri" calls the smallest differential interval obtained by hearing "Shruti" (Sanskrit for "listening"), and usually divides an octave into 22 Shruti. In actual music, two to four Shruti are considered as one interval (called "Swara"). Swara, along with intervals, also has the meaning of pitch. One octave consists of 7 svaras, and their musical scales are called: sarigamapadhani. Shruti is not composed of equal temperament. Due to different schools of music, intervals are also treated differently. Each shruti has a specific meaning, for example, the meaning of shruti "Devra" is "excitement and excitement". Then based on the 7 svaras, three basic types of krama are formed: sa krama, ma krama and kar krama. Among them, the basic scale composed of 7 tones of Sa·Krama and Ma·Krama is used as the basic sound, and has been developed into 14 types of melodies, called "Mrchana". Furthermore, 7 of the 14 spins of Mrchana are developed to the basic spins and form the prototype of the raga (called jati).