Purvanga (or Purvang) and Uttaranga (or Uttarang)

 In Hindustani classical music, the terms Purvanga (or Purvang) and Uttaranga (or Uttarang) refer to the lower and upper halves of the octave (saptak) respectively, and not to specific sections or stages of a khyal performance.

Definitions

• Purvanga (Purvang):
  This denotes the lower tetrachord of the octave, comprising the notes Sa, Re, Ga, and Ma (S R G M).
• Uttaranga (Uttarang):
  This denotes the upper tetrachord, comprising the notes Pa, Dha, Ni, and the upper Sa (P D N S′).

Relevance to Khyal and Raagas

Although these terms do not describe formal parts of a khyal, they are essential for understanding raag structure, melodic emphasis, and time theory:

• Raag Classification:
  Raagas are often classified as Purvanga-vadi or Uttaranga-vadi, depending on whether the vadi (dominant note) lies in the lower or upper half of the octave.
• Melodic Development:
  In a khyal performance, melodic elaboration—such as alap, bol-alap, taans, and sargams—tends to emphasize the register (Purvanga or Uttaranga) that is central to the raag’s identity.
• Time Theory of Raagas:
  This classification is closely linked to the traditional samay siddhant (time theory) of raagas.
• Purvanga-vadi raagas are generally performed during the first half of the day or night (approximately 12 p.m. to 12 a.m.).
• Uttaranga-vadi raagas are typically performed during the second half (approximately 12 a.m. to 12 p.m.).

While a standard khyal performance consists of compositional sections such as sthayi and antara, and is presented in vilambit (slow) and drut (fast) tempos, the terms Purvanga and Uttaranga specifically describe the melodic regions of the octave emphasized within that structure, rather than the performance form itself