This extremely popular evening raga is said to be first sung by Miyan Tansen, a famous court musicians, in the 16th century. It has a tonal base of F yet the tonic (Sa) remains C in this case as Sa can be any of the 12 semitones and you would transpose the intervals accordingly. The use of G (Pa) is interesting as you can use it in an ascending motif as long as it falls back to F (Ma) or Eb (Komal Ga).